cifs: fix race between compound_send_recv() and the demultiplex thread

Commit Message

Ronnie Sahlberg Nov. 14, 2019, 1:42 a.m. UTC

There is a race where the open() may be interrupted between when we receive the reply
but before we have invoked the callback in which case we never end up calling
handle_cancelled_mid() and thus leak an open handle on the server.

Signed-off-by: Ronnie Sahlberg <[e-mail]>
---
 fs/cifs/connect.c   | 1 -
 fs/cifs/transport.c | 3 ++-
 2 files changed, 2 insertions(+), 2 deletions(-)

Patch

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index ccaa8bad336f..802604a7e692 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1223,7 +1223,6 @@  cifs_demultiplex_thread(void *p)
 			if (mids[i] != NULL) {
 				mids[i]->resp_buf_size = server->pdu_size;
 				if ((mids[i]->mid_flags & MID_WAIT_CANCELLED) &&
-				    mids[i]->mid_state == MID_RESPONSE_RECEIVED &&
 				    server->ops->handle_cancelled_mid)
 					server->ops->handle_cancelled_mid(
 							mids[i]->resp_buf,
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index ca3de62688d6..28018a7eccb2 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -1119,7 +1119,8 @@  compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 				 midQ[i]->mid, le16_to_cpu(midQ[i]->command));
 			send_cancel(server, &rqst[i], midQ[i]);
 			spin_lock(&GlobalMid_Lock);
-			if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) {
+			if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED ||
+			    midQ[i]->mid_state == MID_RESPONSE_RECEIVED) {
 				midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
 				midQ[i]->callback = cifs_cancelled_callback;
 				cancelled_mid[i] = true;