From: Laibin Qiu qiulaibin@huawei.com
[ Upstream commit b781d8db580c058ecd54ed7d5dde7f8270b25f5b ]
KASAN reports a use-after-free report when doing block test:
================================================================== [10050.967049] BUG: KASAN: use-after-free in submit_bio_checks+0x1539/0x1550
[10050.977638] Call Trace: [10050.978190] dump_stack+0x9b/0xce [10050.979674] print_address_description.constprop.6+0x3e/0x60 [10050.983510] kasan_report.cold.9+0x22/0x3a [10050.986089] submit_bio_checks+0x1539/0x1550 [10050.989576] submit_bio_noacct+0x83/0xc80 [10050.993714] submit_bio+0xa7/0x330 [10050.994435] mpage_readahead+0x380/0x500 [10050.998009] read_pages+0x1c1/0xbf0 [10051.002057] page_cache_ra_unbounded+0x4c2/0x6f0 [10051.007413] do_page_cache_ra+0xda/0x110 [10051.008207] force_page_cache_ra+0x23d/0x3d0 [10051.009087] page_cache_sync_ra+0xca/0x300 [10051.009970] generic_file_buffered_read+0xbea/0x2130 [10051.012685] generic_file_read_iter+0x315/0x490 [10051.014472] blkdev_read_iter+0x113/0x1b0 [10051.015300] aio_read+0x2ad/0x450 [10051.023786] io_submit_one+0xc8e/0x1d60 [10051.029855] __se_sys_io_submit+0x125/0x350 [10051.033442] do_syscall_64+0x2d/0x40 [10051.034156] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10051.048733] Allocated by task 18598: [10051.049482] kasan_save_stack+0x19/0x40 [10051.050263] __kasan_kmalloc.constprop.1+0xc1/0xd0 [10051.051230] kmem_cache_alloc+0x146/0x440 [10051.052060] mempool_alloc+0x125/0x2f0 [10051.052818] bio_alloc_bioset+0x353/0x590 [10051.053658] mpage_alloc+0x3b/0x240 [10051.054382] do_mpage_readpage+0xddf/0x1ef0 [10051.055250] mpage_readahead+0x264/0x500 [10051.056060] read_pages+0x1c1/0xbf0 [10051.056758] page_cache_ra_unbounded+0x4c2/0x6f0 [10051.057702] do_page_cache_ra+0xda/0x110 [10051.058511] force_page_cache_ra+0x23d/0x3d0 [10051.059373] page_cache_sync_ra+0xca/0x300 [10051.060198] generic_file_buffered_read+0xbea/0x2130 [10051.061195] generic_file_read_iter+0x315/0x490 [10051.062189] blkdev_read_iter+0x113/0x1b0 [10051.063015] aio_read+0x2ad/0x450 [10051.063686] io_submit_one+0xc8e/0x1d60 [10051.064467] __se_sys_io_submit+0x125/0x350 [10051.065318] do_syscall_64+0x2d/0x40 [10051.066082] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[10051.067455] Freed by task 13307: [10051.068136] kasan_save_stack+0x19/0x40 [10051.068931] kasan_set_track+0x1c/0x30 [10051.069726] kasan_set_free_info+0x1b/0x30 [10051.070621] __kasan_slab_free+0x111/0x160 [10051.071480] kmem_cache_free+0x94/0x460 [10051.072256] mempool_free+0xd6/0x320 [10051.072985] bio_free+0xe0/0x130 [10051.073630] bio_put+0xab/0xe0 [10051.074252] bio_endio+0x3a6/0x5d0 [10051.074984] blk_update_request+0x590/0x1370 [10051.075870] scsi_end_request+0x7d/0x400 [10051.076667] scsi_io_completion+0x1aa/0xe50 [10051.077503] scsi_softirq_done+0x11b/0x240 [10051.078344] blk_mq_complete_request+0xd4/0x120 [10051.079275] scsi_mq_done+0xf0/0x200 [10051.080036] virtscsi_vq_done+0xbc/0x150 [10051.080850] vring_interrupt+0x179/0x390 [10051.081650] __handle_irq_event_percpu+0xf7/0x490 [10051.082626] handle_irq_event_percpu+0x7b/0x160 [10051.083527] handle_irq_event+0xcc/0x170 [10051.084297] handle_edge_irq+0x215/0xb20 [10051.085122] asm_call_irq_on_stack+0xf/0x20 [10051.085986] common_interrupt+0xae/0x120 [10051.086830] asm_common_interrupt+0x1e/0x40
==================================================================
Bio will be checked at beginning of submit_bio_noacct(). If bio needs to be throttled, it will start the timer and stop submit bio directly. Bio will submit in blk_throtl_dispatch_work_fn() when the timer expires. But in the current process, if bio is throttled, it will still set bio issue->value by blkcg_bio_issue_init(). This is redundant and may cause the above use-after-free.
CPU0 CPU1 submit_bio submit_bio_noacct submit_bio_checks blk_throtl_bio() <=mod_timer(&sq->pending_timer blk_throtl_dispatch_work_fn submit_bio_noacct() <= bio have throttle tag, will throw directly and bio issue->value will be set here
bio_endio() bio_put() bio_free() <= free this bio
blkcg_bio_issue_init(bio) <= bio has been freed and will lead to UAF return BLK_QC_T_NONE
Fix this by remove extra blkcg_bio_issue_init.
Fixes: e439bedf6b24 (blkcg: consolidate bio_issue_init() to be a part of core) Signed-off-by: Laibin Qiu qiulaibin@huawei.com Link: https://lore.kernel.org/r/20211112093354.3581504-1-qiulaibin@huawei.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-core.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c index 4d8f5fe915887..12aa8c1da6003 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -887,10 +887,8 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio) if (unlikely(!current->io_context)) create_task_io_context(current, GFP_ATOMIC, q->node);
- if (blk_throtl_bio(bio)) { - blkcg_bio_issue_init(bio); + if (blk_throtl_bio(bio)) return false; - }
blk_cgroup_bio_start(bio); blkcg_bio_issue_init(bio);