driver core: fix potential NULL pointer dereference in dev_uevent()
commit 18daa52418e7e4629ed1703b64777294209d2622 upstream.
If userspace reads "uevent" device attribute at the same time as another
threads unbinds the device from its driver, change to dev->driver from a
valid pointer to NULL may result in crash. Fix this by using READ_ONCE()
when fetching the pointer, and take bus' drivers klist lock to make sure
driver instance will not disappear while we access it.
Use WRITE_ONCE() when setting the driver pointer to ensure there is no
tearing.
BUG=b/422951420
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2025-37800 in the Linux kernel.
cos-patch: security-moderate
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250311052417.1846985-3-dmitry.torokhov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: I818b9f80ca15797c5bb58e98b0f098a33acedc30
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/104408
Reviewed-by: Kevin Berry <kpberry@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
3 files changed
