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
