[PATCH 5.17 041/225] ceph: fix possible NULL pointer dereference for req->r_session

[Greg Kroah-Hartman]

From: Xiubo Li <xiubli@xxxxxxxxxx>

commit 7acae6183cf37c48b8da48bbbdb78820fb3913f3 upstream.

The request will be inserted into the ci->i_unsafe_dirops before
assigning the req->r_session, so it's possible that we will hit
NULL pointer dereference bug here.

Cc: stable@xxxxxxxxxxxxxxx
URL: https://tracker.ceph.com/issues/55327
Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Tested-by: Aaron Tomlin <atomlin@xxxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/ceph/caps.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2267,6 +2267,8 @@ retry:
 			list_for_each_entry(req, &ci->i_unsafe_dirops,
 					    r_unsafe_dir_item) {
 				s = req->r_session;
+				if (!s)
+					continue;
 				if (unlikely(s->s_mds >= max_sessions)) {
 					spin_unlock(&ci->i_unsafe_lock);
 					for (i = 0; i < max_sessions; i++) {
@@ -2287,6 +2289,8 @@ retry:
 			list_for_each_entry(req, &ci->i_unsafe_iops,
 					    r_unsafe_target_item) {
 				s = req->r_session;
+				if (!s)
+					continue;
 				if (unlikely(s->s_mds >= max_sessions)) {
 					spin_unlock(&ci->i_unsafe_lock);
 					for (i = 0; i < max_sessions; i++) {