genetlink: fix genl_bind() invoking bind() after -EPERM
[ Upstream commit 1dbfb0363224f6da56f6655d596dc5097308d6f5 ]
Per family bind/unbind callbacks were introduced to allow families
to track multicast group consumer presence, e.g. to start or stop
producing events depending on listeners.
However, in genl_bind() the bind() callback was invoked even if
capability checks failed and ret was set to -EPERM. This means that
callbacks could run on behalf of unauthorized callers while the
syscall still returned failure to user space.
Fix this by only invoking bind() after "if (ret) break;" check
i.e. after permission checks have succeeded.
BUG=b/448601869
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2025-39926 in the Linux kernel.
cos-patch: security-moderate
Fixes: 3de21a8990d3 ("genetlink: Add per family bind/unbind callbacks")
Change-Id: I7faf1af2274cdd80449844f1e0bde8243caca5ab
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Link: https://patch.msgid.link/20250905135731.3026965-1-alok.a.tiwari@oracle.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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/+/113090
Reviewed-by: Kevin Berry <kpberry@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Miri Amarilio <mirilio@google.com>
1 file changed
