diff options
| author | Frank Sorenson <sorenson@redhat.com> | 2026-08-12 21:39:51 -0500 |
|---|---|---|
| committer | Paulo Alcantara <pc@manguebit.org> | 2026-08-24 17:08:53 -0300 |
| commit | 730d0bb19507b9e19c2fe5343109ac618e2fbce5 (patch) | |
| tree | 8168ffbd3ab6735df13c05199ea1c0530f72e310 | |
| parent | 6343c1da561962688f203362d80d6a3bfa39fa1b (diff) | |
smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2
When a valid primary TRANSACT2 response has been received (mid->resp_buf
set, mid->multiRsp true) and a subsequent secondary response causes
cifs_check_trans2() to return false -- either because the SMB header is
invalid (malformed != 0) or because check2ndT2() rejects the PDU --
handle_mid() overwrites mid->resp_buf with the new buffer (leaking the
primary buffer) and, because mid->multiRsp is set, skips the
server->smallbuf/bigbuf NULL-out. When the user thread frees
mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the
demux thread reuses it for the next packet, resulting in a use-after-free.
Combine both early-exit conditions and, when mid->multiRsp is already
set, abort the pending transaction inline: set multiEnd, call
dequeue_mid() with malformed=true, and return true so handle_mid() exits
without touching mid->resp_buf or the server buffer pointers.
Fixes: 316cf94a910f ("CIFS: Move trans2 processing to ops struct")
Cc: stable@vger.kernel.org # cifs_check_trans2() is in smb1ops.c on kernels < 7.0
Signed-off-by: Frank Sorenson <sorenson@redhat.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
| -rw-r--r-- | fs/smb/client/smb1transport.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/fs/smb/client/smb1transport.c b/fs/smb/client/smb1transport.c index 66daa5a37e4a..42e95cc1bd89 100644 --- a/fs/smb/client/smb1transport.c +++ b/fs/smb/client/smb1transport.c @@ -449,10 +449,18 @@ bool cifs_check_trans2(struct mid_q_entry *mid, struct TCP_Server_Info *server, char *buf, int malformed) { - if (malformed) - return false; - if (check2ndT2(buf) <= 0) + if (malformed || check2ndT2(buf) <= 0) { + /* mid->multiRsp blocks the server buf detach in handle_mid(); + * returning false here would leak resp_buf and leave a dangling + * server->smallbuf/bigbuf after the user thread frees resp_buf. + */ + if (mid->multiRsp) { + mid->multiEnd = true; + dequeue_mid(server, mid, true); + return true; + } return false; + } mid->multiRsp = true; if (mid->resp_buf) { /* merge response - fix up 1st*/ |