| Message ID | 20200217210839.28535-4-bvanassche@acm.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Five patches related to changing the number of hardware queues | expand |
On Mon, Feb 17, 2020 at 01:08:37PM -0800, Bart Van Assche wrote: > 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 > > Cc: Christoph Hellwig <hch@infradead.org> > Cc: Ming Lei <ming.lei@redhat.com> > Cc: Hannes Reinecke <hare@suse.com> > Cc: Johannes Thumshirn <jth@kernel.org> > Cc: Keith Busch <kbusch@kernel.org> > Fixes: ac0d6b926e74 ("block: Reduce the amount of memory required per request queue") > Signed-off-by: Bart Van Assche <bvanassche@acm.org> > --- > block/blk-mq.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 2b9f490f5a64..5408098b58f2 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; > } Looks correct, since ->nr_hw_queues needs to be updated after hctxs are initialized successfully: Reviewed-by: Ming Lei <ming.lei@redhat.com> thanks, Ming
diff --git a/block/blk-mq.c b/block/blk-mq.c index 2b9f490f5a64..5408098b58f2 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; }
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 Cc: Christoph Hellwig <hch@infradead.org> Cc: Ming Lei <ming.lei@redhat.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Johannes Thumshirn <jth@kernel.org> Cc: Keith Busch <kbusch@kernel.org> Fixes: ac0d6b926e74 ("block: Reduce the amount of memory required per request queue") Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- block/blk-mq.c | 1 - 1 file changed, 1 deletion(-)