CVE-2019-7308

Published: 1 February 2019

kernel/bpf/verifier.c in the Linux kernel before 4.20.6 performs undesirable out-of-bounds speculation on pointer arithmetic in various cases, including cases of different branches with different state or limits to sanitize, leading to side-channel attacks.

From the Ubuntu Security Team

Jann Horn discovered that the eBPF implementation in the Linux kernel was insufficiently hardened against Spectre V1 attacks. A local attacker could use this to expose sensitive information.

Notes

Mitigation for this vulnerability is available by setting the
kernel.unprivileged_bpf_disabled sysctl to 1:
$ sudo sysctl kernel.unprivileged_bpf_disabled=1
$ echo kernel.unprivileged_bpf_disabled=1 | \
sudo tee /etc/sysctl.d/90-CVE-2019-7308.conf
This issue is mitigated on systems that use secure boot, thanks to
the kernel lockdown feature which blocks BPF program loading.

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-7308
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=979d63d50c0c0f7bc537bf821e056cc9fe5abd38
• https://www.openwall.com/lists/oss-security/2019/02/02/3
• https://ubuntu.com/security/notices/USN-3930-1
• https://ubuntu.com/security/notices/USN-3930-2
• https://ubuntu.com/security/notices/USN-3931-1
• https://ubuntu.com/security/notices/USN-3931-2
• NVD
• Launchpad
• Debian

Bugs

• https://bugs.chromium.org/p/project-zero/issues/detail?id=1711