From 7ddc971f86aa0a4cee9f6886c356a052461957ae Mon Sep 17 00:00:00 2001 From: Mike Krinkin Date: Sat, 30 Jan 2016 19:09:59 +0300 Subject: [PATCH] block: fix use-after-free in dio_bio_complete kasan reported the following error when i ran xfstest: [ 701.826854] ================================================================== [ 701.826864] BUG: KASAN: use-after-free in dio_bio_complete+0x41a/0x600 at addr ffff880080b95f94 [ 701.826870] Read of size 4 by task loop2/3874 [ 701.826879] page:ffffea000202e540 count:0 mapcount:0 mapping: (null) index:0x0 [ 701.826890] flags: 0x100000000000000() [ 701.826895] page dumped because: kasan: bad access detected [ 701.826904] CPU: 3 PID: 3874 Comm: loop2 Tainted: G B W L 4.5.0-rc1-next-20160129 #83 [ 701.826910] Hardware name: LENOVO 23205NG/23205NG, BIOS G2ET95WW (2.55 ) 07/09/2013 [ 701.826917] ffff88008fadf800 ffff88008fadf758 ffffffff81ca67bb 0000000041b58ab3 [ 701.826941] ffffffff830d1e74 ffffffff81ca6724 ffff88008fadf748 ffffffff8161c05c [ 701.826963] 0000000000000282 ffff88008fadf800 ffffed0010172bf2 ffffea000202e540 [ 701.826987] Call Trace: [ 701.826997] [] dump_stack+0x97/0xdc [ 701.827005] [] ? _atomic_dec_and_lock+0xc4/0xc4 [ 701.827014] [] ? __dump_page+0x32c/0x490 [ 701.827023] [] kasan_report_error+0x5f3/0x8b0 [ 701.827033] [] ? dio_bio_complete+0x41a/0x600 [ 701.827040] [] __asan_report_load4_noabort+0x59/0x80 [ 701.827048] [] ? dio_bio_complete+0x41a/0x600 [ 701.827053] [] dio_bio_complete+0x41a/0x600 [ 701.827057] [] ? blk_queue_exit+0x108/0x270 [ 701.827060] [] dio_bio_end_aio+0xa0/0x4d0 [ 701.827063] [] ? dio_bio_complete+0x600/0x600 [ 701.827067] [] ? blk_account_io_completion+0x316/0x5d0 [ 701.827070] [] bio_endio+0x79/0x200 [ 701.827074] [] blk_update_request+0x1df/0xc50 [ 701.827078] [] blk_mq_end_request+0x57/0x120 [ 701.827081] [] __blk_mq_complete_request+0x310/0x590 [ 701.827084] [] ? set_next_entity+0x2f8/0x2ed0 [ 701.827088] [] ? put_prev_entity+0x22d/0x2a70 [ 701.827091] [] blk_mq_complete_request+0x5b/0x80 [ 701.827094] [] loop_queue_work+0x273/0x19d0 [ 701.827098] [] ? finish_task_switch+0x1c8/0x8e0 [ 701.827101] [] ? trace_hardirqs_on_caller+0x18/0x6c0 [ 701.827104] [] ? lo_read_simple+0x890/0x890 [ 701.827108] [] ? debug_check_no_locks_freed+0x350/0x350 [ 701.827111] [] ? __hrtick_start+0x130/0x130 [ 701.827115] [] ? __schedule+0x936/0x20b0 [ 701.827118] [] ? kthread_worker_fn+0x3ed/0x8d0 [ 701.827121] [] ? kthread_worker_fn+0x21d/0x8d0 [ 701.827125] [] ? trace_hardirqs_on_caller+0x18/0x6c0 [ 701.827128] [] kthread_worker_fn+0x2af/0x8d0 [ 701.827132] [] ? __init_kthread_worker+0x170/0x170 [ 701.827135] [] ? _raw_spin_unlock_irqrestore+0x36/0x60 [ 701.827138] [] ? __init_kthread_worker+0x170/0x170 [ 701.827141] [] ? __init_kthread_worker+0x170/0x170 [ 701.827144] [] kthread+0x24b/0x3a0 [ 701.827148] [] ? kthread_create_on_node+0x4c0/0x4c0 [ 701.827151] [] ? trace_hardirqs_on+0xd/0x10 [ 701.827155] [] ? do_group_exit+0xdd/0x350 [ 701.827158] [] ? kthread_create_on_node+0x4c0/0x4c0 [ 701.827161] [] ret_from_fork+0x3f/0x70 [ 701.827165] [] ? kthread_create_on_node+0x4c0/0x4c0 [ 701.827167] Memory state around the buggy address: [ 701.827170] ffff880080b95e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 701.827172] ffff880080b95f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 701.827175] >ffff880080b95f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 701.827177] ^ [ 701.827179] ffff880080b96000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 701.827182] ffff880080b96080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff [ 701.827183] ================================================================== The problem is that bio_check_pages_dirty calls bio_put, so we must not access bio fields after bio_check_pages_dirty. Fixes: 9b81c842355ac96097ba ("block: don't access bio->bi_error after bio_put()"). Signed-off-by: Mike Krinkin Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe --- fs/direct-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/direct-io.c b/fs/direct-io.c index 1b2f7ffc8b84..d6a9012d42ad 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -472,8 +472,8 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio) dio->io_error = -EIO; if (dio->is_async && dio->rw == READ && dio->should_dirty) { - bio_check_pages_dirty(bio); /* transfers ownership */ err = bio->bi_error; + bio_check_pages_dirty(bio); /* transfers ownership */ } else { bio_for_each_segment_all(bvec, bio, i) { struct page *page = bvec->bv_page; -- 2.20.1