Several block drivers call alloc_disk() followed by put_disk() if
something fails before device_add_disk() is called without calling
blk_cleanup_queue(). Make sure that also for this scenario a request
queue is dissociated from the cgroup controller. This patch avoids
that loading the parport_pc, paride and pf drivers triggers the
following kernel crash:
BUG: KASAN: null-ptr-deref in pi_init+0x42e/0x580 [paride]
Read of size 4 at addr 0000000000000008 by task modprobe/744
Call Trace:
dump_stack+0x9a/0xeb
kasan_report+0x139/0x350
pi_init+0x42e/0x580 [paride]
pf_init+0x2bb/0x1000 [pf]
do_one_initcall+0x8e/0x405
do_init_module+0xd9/0x2f2
load_module+0x3ab4/0x4700
SYSC_finit_module+0x176/0x1a0
do_syscall_64+0xee/0x2b0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
Reported-by: Alexandru Moise <00moses.alexander00@xxxxxxxxx>
Fixes: a063057d7c73 ("block: Fix a race between request queue removal and the block cgroup controller")
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
Cc: Alexandru Moise <00moses.alexander00@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
---
block/blk-sysfs.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index f8457d6f0190..2e134da78f82 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -788,11 +788,37 @@ static void blk_free_queue_rcu(struct rcu_head *rcu_head)
static void __blk_release_queue(struct work_struct *work)
{
struct request_queue *q = container_of(work, typeof(*q), release_work);
+ struct blkcg_gq *gq;
if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
blk_stat_remove_callback(q, q->poll_cb);
blk_stat_free_callback(q->poll_cb);
+ if (!blk_queue_dead(q)) {
+ /*
+ * Last reference was dropped without having called
+ * blk_cleanup_queue().
+ */
+ WARN_ONCE(blk_queue_init_done(q),
+ "request queue %p has been registered but blk_cleanup_queue() has not been called for that queue\n",
+ q);
+ bdi_put(q->backing_dev_info);
+ blkcg_exit_queue(q);
+
+ if (q->elevator) {
+ ioc_clear_queue(q);
+ elevator_exit(q, q->elevator);
+ }
+ }
+
+ rcu_read_lock();
+ gq = blkg_lookup(&blkcg_root, q);
+ rcu_read_unlock();
+
+ WARN(gq,
+ "request queue %p is being released but it has not yet been removed from the blkcg controller\n",
+ q);
+
blk_free_queue_stats(q->stats);
blk_exit_rl(q, &q->root_rl);
--
2.16.2
