exec: don't WARN for racy path_noexec check
[ Upstream commit 0d196e7589cefe207d5d41f37a0a28a1fdeeb7c6 ]
Both i_mode and noexec checks wrapped in WARN_ON stem from an artifact
of the previous implementation. They used to legitimately check for the
condition, but that got moved up in two commits:
633fb6ac3980 ("exec: move S_ISREG() check earlier")
0fd338b2d2cd ("exec: move path_noexec() check earlier")
Instead of being removed said checks are WARN_ON'ed instead, which
has some debug value.
However, the spurious path_noexec check is racy, resulting in
unwarranted warnings should someone race with setting the noexec flag.
One can note there is more to perm-checking whether execve is allowed
and none of the conditions are guaranteed to still hold after they were
tested for.
Additionally this does not validate whether the code path did any perm
checking to begin with -- it will pass if the inode happens to be
regular.
Keep the redundant path_noexec() check even though it's mindless
nonsense checking for guarantee that isn't given so drop the WARN.
Reword the commentary and do small tidy ups while here.
BUG=b/378073522
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2024-50010 in the Linux kernel.
cos-patch: security-moderate
Change-Id: Ide65289bd23c060347eab170899a16cfdfc6c9dc
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240805131721.765484-1-mjguzik@gmail.com
[brauner: keep redundant path_noexec() check]
Signed-off-by: Christian Brauner <brauner@kernel.org>
[cascardo: keep exit label and use it]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kernel CVE Triage Automation <cloud-image-kernel-cve-triage-automation@prod.google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/85760
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Anil Altinay <aaltinay@google.com>
Reviewed-by: Shuo Yang <gshuoy@google.com>
1 file changed
