CVE-2025-40306

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

orangefs: fix xattr related buffer overflow…

Willy Tarreau w@1wt.eu forwarded me a message from Disclosure disclosure@aisle.com with the following warning:

The helper xattr_key() uses the pointer variable in the loop condition rather than dereferencing it. As key is incremented, it remains non-NULL (until it runs into unmapped memory), so the loop does not terminate on valid C strings and will walk memory indefinitely, consuming CPU or hanging the thread.

I easily reproduced this with setfattr and getfattr, causing a kernel oops, hung user processes and corrupted orangefs files. Disclosure sent along a diff (not a patch) with a suggested fix, which I based this patch on.

After xattr_key started working right, xfstest generic/069 exposed an xattr related memory leak that lead to OOM. xattr_key returns a hashed key. When adding xattrs to the orangefs xattr cache, orangefs used hash_add, a kernel hashing macro. hash_add also hashes the key using hash_log which resulted in additions to the xattr cache going to the wrong hash bucket. generic/069 tortures a single file and orangefs does a getattr for the xattr security.capability every time. Orangefs negative caches on xattrs which includes a kmalloc. Since adds to the xattr cache were going to the wrong bucket, every getattr for security.capability resulted in another kmalloc, none of which were ever freed.

I changed the two uses of hash_add to hlist_add_head instead and the memory leak ceased and generic/069 quit throwing furniture.

Affected Software

References

• https://git.kernel.org/stable/c/025e880759c279ec64d0f754fe65bf45961da864
• https://git.kernel.org/stable/c/15afebb9597449c444801d1ff0b8d8b311f950ab
• https://git.kernel.org/stable/c/9127d1e90c90e5960c8bc72a4ce2c209691a7021
• https://git.kernel.org/stable/c/bc812574de633cf9a9ad6974490e45f6a4bb5126
• https://git.kernel.org/stable/c/c2ca015ac109fd743fdde27933d59dc5ad46658e
• https://git.kernel.org/stable/c/c6564ff6b53c9a8dc786b6f1c51ae7688273f931
• https://git.kernel.org/stable/c/e09a096104fc65859422817fb2211f35855983fe
• https://git.kernel.org/stable/c/ef892d2bf4f3fa2c8de1677dd307e678bdd3d865