CVE-2026-74729 soc: aspeed: lpc-snoop: Fix usercopy overflow in snoop_file_read
A race condition in the Aspeed LPC snoop driver allows local attackers to read kernel memory or crash the system via concurrent FIFO access.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74729?
CVE-2026-74729 is a vulnerability in Linux, published on 22 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
soc: aspeed: lpc-snoop: Fix usercopy overflow in snoop_file_read
put_fifo_with_discard() acts as both producer and consumer on the kfifo: it calls kfifo_skip() (advances out) and kfifo_put() (advances in) from the IRQ handler without synchronizing with snoop_file_read(), which also consumes via kfifo_to_user(). On SMP systems this concurrent access can leave (in - out) larger than the ring buffer, so __kfifo_to_user()'s clamp to (in - out) is ineffective and kfifo_copy_to_user() can attempt a copy_to_user() past the kmalloc-2k backing store:
usercopy: Kernel memory exposure attempt detected from SLUB object 'kmalloc-2k' (offset 0, size 2049)! kernel BUG at mm/usercopy.c! Call trace: usercopy_abort __check_heap_object __check_object_size kfifo_copy_to_user __kfifo_to_user snoop_file_read vfs_read
Serialize kfifo access with a per-channel spinlock shared between the IRQ handler (producer) and the file reader (consumer). Annotate @fifo with __guarded_by(&lock) and opt the driver into context analysis so the compiler enforces that all fifo access holds the lock.
Which versions are affected by CVE-2026-74729?
How do I fix CVE-2026-74729?
Apply the vendor's patch.
Is CVE-2026-74729 being exploited?
There is no known exploitation of CVE-2026-74729 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74729, DEBIAN-CVE-2026-74729, GHSA-6hj9-w6w6-x26p, UBUNTU-CVE-2026-74729.