virtio_fs_add_queues_sysfs() creates per-queue sysfs kobjects via kobject_create_and_add(). The current code checks the wrong variable after the allocation:

- kobject_create_and_add() may return NULL on failure. - The code incorrectly checks fs->mqs_kobj (the parent kobject), which is expected to be non-NULL at this point. - If kobject_create_and_add() fails, fsvq->kobj is NULL but the code can still call sysfs_create_group(fsvq->kobj, ...), leading to a NULL pointer dereference and kernel panic (DoS).

Fix by validating fsvq->kobj immediately after kobject_create_and_add() and aborting on failure, so sysfs_create_group() is never called with a NULL kobject.

Reported-by: Qianchang Zhao pioooooooooip@gmail.com Reported-by: Zhitong Liu liuzhitong1993@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Qianchang Zhao pioooooooooip@gmail.com --- fs/fuse/virtio_fs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index 6bc7c97b0..b2f6486fe 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -373,7 +373,7 @@ static int virtio_fs_add_queues_sysfs(struct virtio_fs *fs)

sprintf(buff, "%d", i); fsvq->kobj = kobject_create_and_add(buff, fs->mqs_kobj); - if (!fs->mqs_kobj) { + if (!fsvq->kobj) { ret = -ENOMEM; goto out_del; }