From: Xiubo Li <xiubli@redhat.com>
Date: Thu, 10 Nov 2022 13:01:59 +0000 (+0800)
Subject: ceph: fix NULL pointer dereference for req->r_session
X-Git-Tag: v5.15.92~1921
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=855485d31e2ac011c2ce7031674c8b5c73321cc4;p=platform%2Fkernel%2Flinux-rpi.git

ceph: fix NULL pointer dereference for req->r_session

[ Upstream commit 5bd76b8de5b74fa941a6eafee87728a0fe072267 ]

The request's r_session maybe changed when it was forwarded or
resent. Both the forwarding and resending cases the requests will
be protected by the mdsc->mutex.

Cc: stable@vger.kernel.org
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2137955
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index a6e2aaf..be96fe6 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2217,7 +2217,6 @@ static int unsafe_request_wait(struct inode *inode)
 	struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_mds_request *req1 = NULL, *req2 = NULL;
-	unsigned int max_sessions;
 	int ret, err = 0;
 
 	spin_lock(&ci->i_unsafe_lock);
@@ -2236,27 +2235,23 @@ static int unsafe_request_wait(struct inode *inode)
 	spin_unlock(&ci->i_unsafe_lock);
 
 	/*
-	 * The mdsc->max_sessions is unlikely to be changed
-	 * mostly, here we will retry it by reallocating the
-	 * sessions array memory to get rid of the mdsc->mutex
-	 * lock.
-	 */
-retry:
-	max_sessions = mdsc->max_sessions;
-
-	/*
 	 * Trigger to flush the journal logs in all the relevant MDSes
 	 * manually, or in the worst case we must wait at most 5 seconds
 	 * to wait the journal logs to be flushed by the MDSes periodically.
 	 */
-	if ((req1 || req2) && likely(max_sessions)) {
-		struct ceph_mds_session **sessions = NULL;
-		struct ceph_mds_session *s;
+	if (req1 || req2) {
 		struct ceph_mds_request *req;
+		struct ceph_mds_session **sessions;
+		struct ceph_mds_session *s;
+		unsigned int max_sessions;
 		int i;
 
+		mutex_lock(&mdsc->mutex);
+		max_sessions = mdsc->max_sessions;
+
 		sessions = kcalloc(max_sessions, sizeof(s), GFP_KERNEL);
 		if (!sessions) {
+			mutex_unlock(&mdsc->mutex);
 			err = -ENOMEM;
 			goto out;
 		}
@@ -2268,16 +2263,6 @@ retry:
 				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++) {
-						s = sessions[i];
-						if (s)
-							ceph_put_mds_session(s);
-					}
-					kfree(sessions);
-					goto retry;
-				}
 				if (!sessions[s->s_mds]) {
 					s = ceph_get_mds_session(s);
 					sessions[s->s_mds] = s;
@@ -2290,16 +2275,6 @@ retry:
 				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++) {
-						s = sessions[i];
-						if (s)
-							ceph_put_mds_session(s);
-					}
-					kfree(sessions);
-					goto retry;
-				}
 				if (!sessions[s->s_mds]) {
 					s = ceph_get_mds_session(s);
 					sessions[s->s_mds] = s;
@@ -2311,11 +2286,12 @@ retry:
 		/* the auth MDS */
 		spin_lock(&ci->i_ceph_lock);
 		if (ci->i_auth_cap) {
-		      s = ci->i_auth_cap->session;
-		      if (!sessions[s->s_mds])
-			      sessions[s->s_mds] = ceph_get_mds_session(s);
+			s = ci->i_auth_cap->session;
+			if (!sessions[s->s_mds])
+				sessions[s->s_mds] = ceph_get_mds_session(s);
 		}
 		spin_unlock(&ci->i_ceph_lock);
+		mutex_unlock(&mdsc->mutex);
 
 		/* send flush mdlog request to MDSes */
 		for (i = 0; i < max_sessions; i++) {