From: Weiping Zhang zhangweiping@didiglobal.com
[ Upstream commit aa880ad690ab6d4c53934af85fb5a43e69ecb0f5 ]
When we increase hardware queue count, blk_mq_update_queue_map will reset the mapping between cpu and hardware queue base on the hardware queue count(set->nr_hw_queues). The mapping cannot be reset if it encounters error in blk_mq_realloc_hw_ctxs, but the fallback flow will continue using it, then blk_mq_map_swqueue will touch a invalid memory, because the mapping points to a wrong hctx.
blktest block/030:
null_blk: module loaded Increasing nr_hw_queues to 8 fails, fallback to 1 ================================================================== BUG: KASAN: null-ptr-deref in blk_mq_map_swqueue+0x2f2/0x830 Read of size 8 at addr 0000000000000128 by task nproc/8541
CPU: 5 PID: 8541 Comm: nproc Not tainted 5.7.0-rc4-dbg+ #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4-rebuilt.opensuse.org 04/01/2014 Call Trace: dump_stack+0xa5/0xe6 __kasan_report.cold+0x65/0xbb kasan_report+0x45/0x60 check_memory_region+0x15e/0x1c0 __kasan_check_read+0x15/0x20 blk_mq_map_swqueue+0x2f2/0x830 __blk_mq_update_nr_hw_queues+0x3df/0x690 blk_mq_update_nr_hw_queues+0x32/0x50 nullb_device_submit_queues_store+0xde/0x160 [null_blk] configfs_write_file+0x1c4/0x250 [configfs] __vfs_write+0x4c/0x90 vfs_write+0x14b/0x2d0 ksys_write+0xdd/0x180 __x64_sys_write+0x47/0x50 do_syscall_64+0x6f/0x310 entry_SYSCALL_64_after_hwframe+0x49/0xb3
Signed-off-by: Weiping Zhang zhangweiping@didiglobal.com Tested-by: Bart van Assche bvanassche@acm.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-mq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c index 22ce0c6a8e6a..0550366e25d8 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3304,8 +3304,8 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
prev_nr_hw_queues = set->nr_hw_queues; set->nr_hw_queues = nr_hw_queues; - blk_mq_update_queue_map(set); fallback: + blk_mq_update_queue_map(set); list_for_each_entry(q, &set->tag_list, tag_set_list) { blk_mq_realloc_hw_ctxs(set, q); if (q->nr_hw_queues != set->nr_hw_queues) {