CVE-2025-40320

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

smb: client: fix potential cfid UAF in smb2_query_info_compound

When smb2_query_info_compound() retries, a previously allocated cfid may

have been freed in the first attempt.

Because cfid wasn't reset on replay, later cleanup could act on a stale

pointer, leading to a potential use-after-free.

Reinitialize cfid to NULL under the replay label.

Example trace (trimmed):

refcount_t: underflow; use-after-free.

WARNING: CPU: 1 PID: 11224 at ../lib/refcount.c:28 refcount_warn_saturate+0x9c/0x110

[...]

RIP: 0010:refcount_warn_saturate+0x9c/0x110

[...]

Call Trace:

<TASK>

smb2_query_info_compound+0x29c/0x5c0 [cifs f90b72658819bd21c94769b6a652029a07a7172f]

? step_into+0x10d/0x690

? __legitimize_path+0x28/0x60

smb2_queryfs+0x6a/0xf0 [cifs f90b72658819bd21c94769b6a652029a07a7172f]

smb311_queryfs+0x12d/0x140 [cifs f90b72658819bd21c94769b6a652029a07a7172f]

? kmem_cache_alloc+0x18a/0x340

? getname_flags+0x46/0x1e0

cifs_statfs+0x9f/0x2b0 [cifs f90b72658819bd21c94769b6a652029a07a7172f]

statfs_by_dentry+0x67/0x90

vfs_statfs+0x16/0xd0

user_statfs+0x54/0xa0

__do_sys_statfs+0x20/0x50

do_syscall_64+0x58/0x80