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authorBart Van Assche <bvanassche@acm.org>2020-03-09 21:26:18 -0700
committerJens Axboe <axboe@kernel.dk>2020-03-10 07:09:59 -0600
commitd0930bb8f46b8fb4a7d429c0bf1c91b3ed00a7cf (patch)
tree698686cf841670bf3de44b08bf5e8062f6d95592 /block/blk-mq.c
parent6e66b49392419f3fe134e1be583323ef75da1e4b (diff)
blk-mq: Fix a recently introduced regression in blk_mq_realloc_hw_ctxs()
q->nr_hw_queues must only be updated once it is known that blk_mq_realloc_hw_ctxs() has succeeded. Otherwise it can happen that reallocation fails and that q->nr_hw_queues is larger than the number of allocated hardware queues. This patch fixes the following crash if increasing the number of hardware queues fails: BUG: KASAN: null-ptr-deref in blk_mq_map_swqueue+0x775/0x810 Write of size 8 at addr 0000000000000118 by task check/977 CPU: 3 PID: 977 Comm: check Not tainted 5.6.0-rc1-dbg+ #8 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: dump_stack+0xa5/0xe6 __kasan_report.cold+0x65/0x99 kasan_report+0x16/0x20 check_memory_region+0x140/0x1b0 memset+0x28/0x40 blk_mq_map_swqueue+0x775/0x810 blk_mq_update_nr_hw_queues+0x468/0x710 nullb_device_submit_queues_store+0xf7/0x1a0 [null_blk] configfs_write_file+0x1c4/0x250 [configfs] __vfs_write+0x4c/0x90 vfs_write+0x145/0x2c0 ksys_write+0xd7/0x180 __x64_sys_write+0x47/0x50 do_syscall_64+0x6f/0x2f0 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: ac0d6b926e74 ("block: Reduce the amount of memory required per request queue") Signed-off-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Cc: Keith Busch <kbusch@kernel.org> Cc: Johannes Thumshirn <jth@kernel.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-mq.c')
-rw-r--r--block/blk-mq.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index d4bd9b961726..37ff8dfb8ab9 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2824,7 +2824,6 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
memcpy(new_hctxs, hctxs, q->nr_hw_queues *
sizeof(*hctxs));
q->queue_hw_ctx = new_hctxs;
- q->nr_hw_queues = set->nr_hw_queues;
kfree(hctxs);
hctxs = new_hctxs;
}