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@gmail.com Fixes: a063057d7c73 ("block: Fix a race between request queue removal and the block cgroup controller") # v4.17 Signed-off-by: Bart Van Assche bart.vanassche@wdc.com Tested-by: Alexandru Moise 00moses.alexander00@gmail.com Reviewed-by: Johannes Thumshirn jthumshirn@suse.de Cc: Tejun Heo tj@kernel.org Cc: Christoph Hellwig hch@lst.de Cc: Ming Lei ming.lei@redhat.com Cc: Alexandru Moise 00moses.alexander00@gmail.com Cc: Joseph Qi joseph.qi@linux.alibaba.com Cc: stable@vger.kernel.org --- block/blk-sysfs.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index ca1984ecbdeb..fcadea471779 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -802,6 +802,21 @@ static void __blk_release_queue(struct work_struct *work) 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); + blk_exit_queue(q); + } + + WARN(blkg_root_lookup(q), + "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);