CVE-2025-40306

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

orangefs: fix xattr related buffer overflow...

Willy Tarreau [email protected] ↗ forwarded me a message from Disclosure [email protected] ↗ 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.

This vulnerability does not affect Red Hat Enterprise Linux as the OrangeFS file system driver is neither enabled nor distributed in standard Red Hat kernels. The upstream flaw involves faulty extended attribute processing in OrangeFS, which could permit a local user to cause out-of-bounds memory reads, thread hangs, or memory exhaustion during filesystem operations. Because Red Hat kernels do not compile or ship the affected driver, supported environments remain unimpacted in default configurations.