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ceph: fix NULL pointer dereference for req->r_session

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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>
This commit is contained in:
Xiubo Li 2022-11-10 21:01:59 +08:00 committed by Ilya Dryomov
parent 51884d153f
commit 5bd76b8de5
1 changed files with 12 additions and 36 deletions
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42
fs/ceph/caps.c
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@ -2248,7 +2248,6 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(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);
@ -2266,28 +2265,24 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(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;
}
@ -2299,16 +2294,6 @@ 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;
@ -2321,16 +2306,6 @@ 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;
@ -2347,6 +2322,7 @@ retry:
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++) {