cifs: Fix use-after-free in SMB2_write

There is a KASAN use-after-free:
BUG: KASAN: use-after-free in SMB2_write+0x1342/0x1580
Read of size 8 at addr ffff8880b6a8e450 by task ln/4196

Should not release the 'req' because it will use in the trace.

Fixes: eccb4422cf97 ("smb3: Add ftrace tracepoints for improved SMB3 debugging")
Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org> 4.18+
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 21ad01d55ab2d32f0a4406c4cd0704cfab80026a..5d1f8d2d44e432399ba3573fd1904cb65c372fb5 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3769,7 +3769,6 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
 
        rc = cifs_send_recv(xid, io_parms->tcon->ses, &rqst,
                            &resp_buftype, flags, &rsp_iov);
-       cifs_small_buf_release(req);
        rsp = (struct smb2_write_rsp *)rsp_iov.iov_base;
 
        if (rc) {
@@ -3787,6 +3786,7 @@ SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
                                     io_parms->offset, *nbytes);
        }
 
+       cifs_small_buf_release(req);
        free_rsp_buf(resp_buftype, rsp);
        return rc;
 }