CVE-2025-38724

In the Linux kernel, the following vulnerability has been resolved:

nfsd: handle get_client_locked() failure in nfsd4_setclientid_confirm()

Lei Lu recently reported that nfsd4_setclientid_confirm() did not check the return value from get_client_locked(). a SETCLIENTID_CONFIRM could race with a confirmed client expiring and fail to get a reference. That could later lead to a UAF.

Fix this by getting a reference early in the case where there is an extant confirmed client. If that fails then treat it as if there were no confirmed client found at all.

In the case where the unconfirmed client is expiring, just fail and return the result from get_client_locked().

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/22f45cedf281e6171817c8a3432c44d788c550e1
• https://git.kernel.org/stable/c/36e83eda90e0e4ac52f259f775b40b2841f8a0a3
• https://git.kernel.org/stable/c/3f252a73e81aa01660cb426735eab932e6182e8d
• https://git.kernel.org/stable/c/571a5e46c71490285d2d8c06f6b5a7cbf6c7edd1
• https://git.kernel.org/stable/c/74ad36ed60df561a303a19ecef400c7096b20306
• https://git.kernel.org/stable/c/908e4ead7f757504d8b345452730636e298cbf68
• https://git.kernel.org/stable/c/d35ac850410966010e92f401f4e21868a9ea4d8b
• https://git.kernel.org/stable/c/d71abd1ae4e0413707cd42b10c24a11d1aa71772
• https://git.kernel.org/stable/c/f3aac6cf390d8b80e1d82975faf4ac61175519c0
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
• https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html