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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
        Ming Lei <ming.lei@redhat.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Jens Axboe <axboe@kernel.dk>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 53/84] block: Fix handling of offline queues in blk_mq_alloc_request_hctx()
Date:   Mon, 20 Jun 2022 14:51:16 +0200
Message-Id: <20220620124722.460728971@linuxfoundation.org>
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From: Bart Van Assche <bvanassche@acm.org>

[ Upstream commit 14dc7a18abbe4176f5626c13c333670da8e06aa1 ]

This patch prevents that test nvme/004 triggers the following:

UBSAN: array-index-out-of-bounds in block/blk-mq.h:135:9
index 512 is out of range for type 'long unsigned int [512]'
Call Trace:
 show_stack+0x52/0x58
 dump_stack_lvl+0x49/0x5e
 dump_stack+0x10/0x12
 ubsan_epilogue+0x9/0x3b
 __ubsan_handle_out_of_bounds.cold+0x44/0x49
 blk_mq_alloc_request_hctx+0x304/0x310
 __nvme_submit_sync_cmd+0x70/0x200 [nvme_core]
 nvmf_connect_io_queue+0x23e/0x2a0 [nvme_fabrics]
 nvme_loop_connect_io_queues+0x8d/0xb0 [nvme_loop]
 nvme_loop_create_ctrl+0x58e/0x7d0 [nvme_loop]
 nvmf_create_ctrl+0x1d7/0x4d0 [nvme_fabrics]
 nvmf_dev_write+0xae/0x111 [nvme_fabrics]
 vfs_write+0x144/0x560
 ksys_write+0xb7/0x140
 __x64_sys_write+0x42/0x50
 do_syscall_64+0x35/0x80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Fixes: 20e4d8139319 ("blk-mq: simplify queue mapping & schedule with each possisble CPU")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220615210004.1031820-1-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, 2 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 15a11a217cd0..c5d82b21a1cc 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -466,6 +466,8 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
 	if (!blk_mq_hw_queue_mapped(data.hctx))
 		goto out_queue_exit;
 	cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
+	if (cpu >= nr_cpu_ids)
+		goto out_queue_exit;
 	data.ctx = __blk_mq_get_ctx(q, cpu);
 
 	if (!q->elevator)
-- 
2.35.1