CVE-2021-47289
Publication date 21 May 2024
Last updated 25 October 2024
Ubuntu priority
In the Linux kernel, the following vulnerability has been resolved: ACPI: fix NULL pointer dereference Commit 71f642833284 ("ACPI: utils: Fix reference counting in for_each_acpi_dev_match()") started doing "acpi_dev_put()" on a pointer that was possibly NULL. That fails miserably, because that helper inline function is not set up to handle that case. Just make acpi_dev_put() silently accept a NULL pointer, rather than calling down to put_device() with an invalid offset off that NULL pointer.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| linux | 24.10 oracular |
Not affected
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-88.99
|
|
| 18.04 LTS bionic | Ignored ESM criteria, was needed | |
| 16.04 LTS xenial | Ignored ESM criteria, was needed | |
| 14.04 LTS trusty | Ignored ESM criteria, was needed | |
| linux-allwinner-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored end of kernel support | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws | 24.10 oracular |
Not affected
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-1057.60
|
|
| 18.04 LTS bionic | Ignored ESM criteria, was needed | |
| 16.04 LTS xenial | Ignored ESM criteria, was needed | |
| 14.04 LTS trusty | Ignored ESM criteria, was needed | |
| linux-aws-5.0 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-aws-5.3 | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-5.11 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-aws-5.13 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-5.13 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-aws-5.15 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-aws-6.2 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-5.3 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-aws-5.4 | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic |
Fixed 5.4.0-1057.60~18.04.1
|
|
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-5.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-aws-5.11 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-6.2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-aws-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-fips | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Ignored end of standard support | |
| 14.04 LTS trusty | Not in release | |
| linux-aws-hwe | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Ignored ESM criteria, was needed | |
| 14.04 LTS trusty | Not in release | |
| linux-azure | 24.10 oracular |
Not affected
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-1059.62
|
|
| 18.04 LTS bionic | Ignored superseded by linux-azure-5.3 | |
| 16.04 LTS xenial | Ignored ESM criteria, was needed | |
| 14.04 LTS trusty | Ignored ESM criteria, was needed | |
| linux-azure-4.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored ESM criteria, was needed | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-5.11 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-azure-5.13 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-5.13 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-azure-5.15 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-azure-6.2 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-5.3 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-azure-5.4 | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic |
Fixed 5.4.0-1059.62~18.04.1
|
|
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-5.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-azure-5.11 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-6.2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-azure-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-edge | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-azure-5.3 | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-fde | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Ignored superseded by linux-azure-fde-5.15 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-fde-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-fde-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-azure-fde-6.2 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-fde-6.2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored replaced by linux-azure-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-azure-fips | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Ignored end of standard support | |
| 14.04 LTS trusty | Not in release | |
| linux-bluefield | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Fixed 5.4.0-1019.22
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-fips | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp | 24.10 oracular |
Not affected
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-1053.57
|
|
| 18.04 LTS bionic | Ignored superseded by linux-gcp-5.3 | |
| 16.04 LTS xenial | Ignored ESM criteria, was needed | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-4.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored ESM criteria, was needed | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-5.11 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-gcp-5.13 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-5.13 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-gcp-5.15 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-gcp-6.2 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-5.3 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-gcp-5.4 | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic |
Fixed 5.4.0-1053.57~18.04.1
|
|
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-5.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-gcp-5.11 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-6.2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-gcp-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gcp-fips | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Ignored end of standard support | |
| 14.04 LTS trusty | Not in release | |
| linux-gke | 24.10 oracular | Not in release |
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Ignored end of kernel support | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Ignored end of standard support | |
| 14.04 LTS trusty | Not in release | |
| linux-gke-4.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-gke-5.0 | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gke-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored end of kernel support | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gke-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored end of kernel support | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gkeop | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-1024.25
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gkeop-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-gkeop-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored end of kernel support | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored replaced by linux-hwe-5.4 | |
| 16.04 LTS xenial | Ignored ESM criteria, was needed | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-5.11 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-hwe-5.13 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-5.13 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-hwe-5.15 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-hwe-6.2 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic |
Fixed 5.4.0-87.98~18.04.1
|
|
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-5.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-hwe-5.11 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-6.2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-hwe-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-hwe-edge | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-hwe-5.4 | |
| 16.04 LTS xenial | Ignored superseded by linux-hwe | |
| 14.04 LTS trusty | Not in release | |
| linux-ibm | 24.10 oracular | Not in release |
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-1005.6
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-ibm-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-ibm-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic |
Not affected
|
|
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-intel | 24.10 oracular | Not in release |
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-intel-5.13 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored end of kernel support | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-intel-iot-realtime | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-intel-iotg | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-intel-iotg-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-iot | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-kvm | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-1047.49
|
|
| 18.04 LTS bionic | Ignored ESM criteria, was needed | |
| 16.04 LTS xenial | Ignored ESM criteria, was needed | |
| 14.04 LTS trusty | Not in release | |
| linux-laptop | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-lowlatency | 24.10 oracular |
Not affected
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-lowlatency-hwe-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-lowlatency-hwe-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-lowlatency-hwe-6.2 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-lowlatency-hwe-6.2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-lowlatency-hwe-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-lowlatency-hwe-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-lowlatency-hwe-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-lts-xenial | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Ignored ESM criteria, was needed | |
| linux-nvidia | 24.10 oracular | Not in release |
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-nvidia-6.2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-nvidia-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-nvidia-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-nvidia-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-nvidia-lowlatency | 24.10 oracular | Not in release |
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored replaced by linux-hwe-5.4 | |
| 16.04 LTS xenial | Ignored end of standard support | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-5.10 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-oem-5.13 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-5.13 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-oem-5.14 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-5.14 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored replaced by linux-hwe-5.15 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-5.17 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-oem-6.1 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-5.6 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-oem-5.10 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-6.0 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-oem-6.1 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-6.1 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-oem-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oem-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle | 24.10 oracular |
Not affected
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-1055.59
|
|
| 18.04 LTS bionic | Ignored ESM criteria, was needed | |
| 16.04 LTS xenial | Ignored ESM criteria, was needed | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-5.0 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-oracle-5.3 | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-5.11 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-oracle-5.13 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-5.13 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-oracle-5.15 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-5.3 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Ignored superseded by linux-oracle-5.4 | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic |
Fixed 5.4.0-1055.59~18.04.1
|
|
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-5.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-oracle-5.11 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-oracle-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-raspi | 24.10 oracular |
Not affected
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Fixed 5.4.0-1044.48
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-raspi-5.4 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic |
Fixed 5.4.0-1044.48~18.04.1
|
|
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-raspi-realtime | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-raspi2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored replaced by linux-raspi | |
| 18.04 LTS bionic | Ignored end of standard support | |
| 16.04 LTS xenial | Ignored end of standard support | |
| 14.04 LTS trusty | Not in release | |
| linux-realtime | 24.10 oracular |
Not affected
|
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by Ubuntu Pro ppa version | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-riscv | 24.10 oracular |
Not affected
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy | Ignored end of kernel support | |
| 20.04 LTS focal | Ignored superseded by linux-riscv-5.8 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-riscv-5.11 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-riscv-5.13 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-riscv-5.15 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-riscv-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored end of kernel support | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-riscv-5.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Ignored superseded by linux-riscv-5.11 | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-riscv-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-riscv-6.8 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-starfive | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-starfive-5.19 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored end of kernel support | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-starfive-6.2 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Ignored superseded by linux-starfive-6.5 | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-starfive-6.5 | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| linux-xilinx-zynqmp | 24.10 oracular | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release |
References
Other references
- https://www.cve.org/CVERecord?id=CVE-2021-47289
- https://git.kernel.org/linus/fc68f42aa737dc15e7665a4101d4168aadb8e4c4 (5.14-rc3)
- https://git.kernel.org/stable/c/38f54217b423c0101d03a00feec6fb8ec608b12e
- https://git.kernel.org/stable/c/cae3fa3d8165761f3000f523b11cfa1cd35206bc
- https://git.kernel.org/stable/c/ccf23a0888077a25a0793a746c3941db2a7562e4
- https://git.kernel.org/stable/c/fc68f42aa737dc15e7665a4101d4168aadb8e4c4