cifs: Fix use-after-free in SMB2_read

There is a KASAN use-after-free: BUG: KASAN: use-after-free in SMB2_read+0x1136/0x1190 Read of size 8 at addr ffff8880b4e45e50 by task ln/1009 Should not release the 'req' because it will use in the trace. Fixes: eccb442 ("smb3: Add ftrace tracepoints for improved SMB3 debugging") Signed-off-by: ZhangXiaoxu <[email protected]> Signed-off-by: Steve French <[email protected]> CC: Stable <[email protected]> 4.18+ Reviewed-by: Pavel Shilovsky <[email protected]>
OpenDingux · Apr 16, 2019 · 088aaf1 · 088aaf1
1 parent 6a3eb33
commit 088aaf1
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
@@ -3448,8 +3448,6 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
 	rqst.rq_nvec = 1;
 
 	rc = cifs_send_recv(xid, ses, &rqst, &resp_buftype, flags, &rsp_iov);
-	cifs_small_buf_release(req);
-
 	rsp = (struct smb2_read_rsp *)rsp_iov.iov_base;
 
 	if (rc) {
@@ -3471,6 +3469,8 @@ SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
 				    io_parms->tcon->tid, ses->Suid,
 				    io_parms->offset, io_parms->length);
 
+	cifs_small_buf_release(req);
+
 	*nbytes = le32_to_cpu(rsp->DataLength);
 	if ((*nbytes > CIFS_MAX_MSGSIZE) ||
 	    (*nbytes > io_parms->length)) {