[SRU][Focal][PATCH 0/1] CVE-2021-4001

[Jacob Martin]

[Impact]
 It was discovered that the eBPF implementation in the Linux kernel
 contained a race condition around read-only maps. A privileged attacker
 could use this to modify read-only maps.

[Backport]
 Memory mapping and batch support for BPF maps are not present in
 focal:linux, so changes to missing functions were omitted, and writecnt
 was added to struct bpf_map.

[Test]
 Compile and boot tested. Verified prior-working race using userfaultfd
 was no longer achievable with patch applied.

[Potential Regression]
 This change affects the kernel's BPF subsystem. 

Daniel Borkmann (1):
  bpf: Fix toctou on read-only map's constant scalar tracking

 include/linux/bpf.h   |  2 ++
 kernel/bpf/syscall.c  | 25 +++++++++++++++++++++++++
 kernel/bpf/verifier.c | 18 +++++++++++++++++-
 3 files changed, 44 insertions(+), 1 deletion(-)

-- 
2.34.1