From: Henrique Carvalho <henrique.carvalho@suse.com>
To: sfrench@samba.org
Cc: pc@manguebit.org, ronniesahlberg@gmail.com,
sprasad@microsoft.com, tom@talpey.com, bharathsm@microsoft.com,
ematsumiya@suse.de, linux-cifs@vger.kernel.org
Subject: [PATCH] smb: client: fix potential cfid UAF in smb2_query_info_compound
Date: Mon, 27 Oct 2025 18:29:19 -0300 [thread overview]
Message-ID: <20251027212919.2082212-1-henrique.carvalho@suse.com> (raw)
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
Fixes: 4f1fffa237692 ("cifs: commands that are retried should have replay flag set")
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
---
fs/smb/client/smb2ops.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 0f9130ef2e7d..1e39f2165e42 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -2799,11 +2799,12 @@ smb2_query_info_compound(const unsigned int xid, struct cifs_tcon *tcon,
struct cifs_fid fid;
int rc;
__le16 *utf16_path;
- struct cached_fid *cfid = NULL;
+ struct cached_fid *cfid;
int retries = 0, cur_sleep = 1;
replay_again:
/* reinitialize for possible replay */
+ cfid = NULL;
flags = CIFS_CP_CREATE_CLOSE_OP;
oplock = SMB2_OPLOCK_LEVEL_NONE;
server = cifs_pick_channel(ses);
--
2.50.1
next reply other threads:[~2025-10-27 21:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-27 21:29 Henrique Carvalho [this message]
2025-10-28 0:32 ` [PATCH] smb: client: fix potential cfid UAF in smb2_query_info_compound Steve French
2025-10-28 6:02 ` Shyam Prasad N
2025-10-28 13:43 ` Steve French
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