| Message ID | 20240902130329.3787024-2-yukuai1@huaweicloud.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block, bfq: fix corner cases related to bfqq merging | expand |
On Mon 02-09-24 21:03:26, Yu Kuai wrote: > From: Yu Kuai <yukuai3@huawei.com> > > 1) initial state, three tasks: > > Process 1 Process 2 Process 3 > (BIC1) (BIC2) (BIC3) > | Λ | Λ | Λ > | | | | | | > V | V | V | > bfqq1 bfqq2 bfqq3 > process ref: 1 1 1 > > 2) bfqq1 merged to bfqq2: > > Process 1 Process 2 Process 3 > (BIC1) (BIC2) (BIC3) > | | | Λ > \--------------\| | | > V V | > bfqq1--------->bfqq2 bfqq3 > process ref: 0 2 1 > > 3) bfqq2 merged to bfqq3: > > Process 1 Process 2 Process 3 > (BIC1) (BIC2) (BIC3) > here -> Λ | | > \--------------\ \-------------\| > V V > bfqq1--------->bfqq2---------->bfqq3 > process ref: 0 1 3 > > In this case, IO from Process 1 will get bfqq2 from BIC1 first, and then > get bfqq3 through merge chain, and finially handle IO by bfqq3. > Howerver, current code will think bfqq2 is owned by BIC1, like initial > state, and set bfqq2->bic to BIC1. > > bfq_insert_request > -> by Process 1 > bfqq = bfq_init_rq(rq) > bfqq = bfq_get_bfqq_handle_split > bfqq = bic_to_bfqq > -> get bfqq2 from BIC1 > bfqq->ref++ > rq->elv.priv[0] = bic > rq->elv.priv[1] = bfqq > if (bfqq_process_refs(bfqq) == 1) > bfqq->bic = bic > -> record BIC1 to bfqq2 > > __bfq_insert_request > new_bfqq = bfq_setup_cooperator > -> get bfqq3 from bfqq2->new_bfqq > bfqq_request_freed(bfqq) > new_bfqq->ref++ > rq->elv.priv[1] = new_bfqq > -> handle IO by bfqq3 > > Fix the problem by checking bfqq is from merge chain fist. And this > might fix a following problem reported by our syzkaller(unreproducible): > > ================================================================== > BUG: KASAN: slab-use-after-free in bfq_do_early_stable_merge block/bfq-iosched.c:5692 [inline] > BUG: KASAN: slab-use-after-free in bfq_do_or_sched_stable_merge block/bfq-iosched.c:5805 [inline] > BUG: KASAN: slab-use-after-free in bfq_get_queue+0x25b0/0x2610 block/bfq-iosched.c:5889 > Write of size 1 at addr ffff888123839eb8 by task kworker/0:1H/18595 > > CPU: 0 PID: 18595 Comm: kworker/0:1H Tainted: G L 6.6.0-07439-gba2303cacfda #6 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > Workqueue: kblockd blk_mq_requeue_work > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0x91/0xf0 lib/dump_stack.c:106 > print_address_description mm/kasan/report.c:364 [inline] > print_report+0x10d/0x610 mm/kasan/report.c:475 > kasan_report+0x8e/0xc0 mm/kasan/report.c:588 > bfq_do_early_stable_merge block/bfq-iosched.c:5692 [inline] > bfq_do_or_sched_stable_merge block/bfq-iosched.c:5805 [inline] > bfq_get_queue+0x25b0/0x2610 block/bfq-iosched.c:5889 > bfq_get_bfqq_handle_split+0x169/0x5d0 block/bfq-iosched.c:6757 > bfq_init_rq block/bfq-iosched.c:6876 [inline] > bfq_insert_request block/bfq-iosched.c:6254 [inline] > bfq_insert_requests+0x1112/0x5cf0 block/bfq-iosched.c:6304 > blk_mq_insert_request+0x290/0x8d0 block/blk-mq.c:2593 > blk_mq_requeue_work+0x6bc/0xa70 block/blk-mq.c:1502 > process_one_work kernel/workqueue.c:2627 [inline] > process_scheduled_works+0x432/0x13f0 kernel/workqueue.c:2700 > worker_thread+0x6f2/0x1160 kernel/workqueue.c:2781 > kthread+0x33c/0x440 kernel/kthread.c:388 > ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:305 > </TASK> > > Allocated by task 20776: > kasan_save_stack+0x20/0x40 mm/kasan/common.c:45 > kasan_set_track+0x25/0x30 mm/kasan/common.c:52 > __kasan_slab_alloc+0x87/0x90 mm/kasan/common.c:328 > kasan_slab_alloc include/linux/kasan.h:188 [inline] > slab_post_alloc_hook mm/slab.h:763 [inline] > slab_alloc_node mm/slub.c:3458 [inline] > kmem_cache_alloc_node+0x1a4/0x6f0 mm/slub.c:3503 > ioc_create_icq block/blk-ioc.c:370 [inline] > ioc_find_get_icq+0x180/0xaa0 block/blk-ioc.c:436 > bfq_prepare_request+0x39/0xf0 block/bfq-iosched.c:6812 > blk_mq_rq_ctx_init.isra.7+0x6ac/0xa00 block/blk-mq.c:403 > __blk_mq_alloc_requests+0xcc0/0x1070 block/blk-mq.c:517 > blk_mq_get_new_requests block/blk-mq.c:2940 [inline] > blk_mq_submit_bio+0x624/0x27c0 block/blk-mq.c:3042 > __submit_bio+0x331/0x6f0 block/blk-core.c:624 > __submit_bio_noacct_mq block/blk-core.c:703 [inline] > submit_bio_noacct_nocheck+0x816/0xb40 block/blk-core.c:732 > submit_bio_noacct+0x7a6/0x1b50 block/blk-core.c:826 > xlog_write_iclog+0x7d5/0xa00 fs/xfs/xfs_log.c:1958 > xlog_state_release_iclog+0x3b8/0x720 fs/xfs/xfs_log.c:619 > xlog_cil_push_work+0x19c5/0x2270 fs/xfs/xfs_log_cil.c:1330 > process_one_work kernel/workqueue.c:2627 [inline] > process_scheduled_works+0x432/0x13f0 kernel/workqueue.c:2700 > worker_thread+0x6f2/0x1160 kernel/workqueue.c:2781 > kthread+0x33c/0x440 kernel/kthread.c:388 > ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:305 > > Freed by task 946: > kasan_save_stack+0x20/0x40 mm/kasan/common.c:45 > kasan_set_track+0x25/0x30 mm/kasan/common.c:52 > kasan_save_free_info+0x2b/0x50 mm/kasan/generic.c:522 > ____kasan_slab_free mm/kasan/common.c:236 [inline] > __kasan_slab_free+0x12c/0x1c0 mm/kasan/common.c:244 > kasan_slab_free include/linux/kasan.h:164 [inline] > slab_free_hook mm/slub.c:1815 [inline] > slab_free_freelist_hook mm/slub.c:1841 [inline] > slab_free mm/slub.c:3786 [inline] > kmem_cache_free+0x118/0x6f0 mm/slub.c:3808 > rcu_do_batch+0x35c/0xe30 kernel/rcu/tree.c:2189 > rcu_core+0x819/0xd90 kernel/rcu/tree.c:2462 > __do_softirq+0x1b0/0x7a2 kernel/softirq.c:553 > > Last potentially related work creation: > kasan_save_stack+0x20/0x40 mm/kasan/common.c:45 > __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492 > __call_rcu_common kernel/rcu/tree.c:2712 [inline] > call_rcu+0xce/0x1020 kernel/rcu/tree.c:2826 > ioc_destroy_icq+0x54c/0x830 block/blk-ioc.c:105 > ioc_release_fn+0xf0/0x360 block/blk-ioc.c:124 > process_one_work kernel/workqueue.c:2627 [inline] > process_scheduled_works+0x432/0x13f0 kernel/workqueue.c:2700 > worker_thread+0x6f2/0x1160 kernel/workqueue.c:2781 > kthread+0x33c/0x440 kernel/kthread.c:388 > ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:305 > > Second to last potentially related work creation: > kasan_save_stack+0x20/0x40 mm/kasan/common.c:45 > __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492 > __call_rcu_common kernel/rcu/tree.c:2712 [inline] > call_rcu+0xce/0x1020 kernel/rcu/tree.c:2826 > ioc_destroy_icq+0x54c/0x830 block/blk-ioc.c:105 > ioc_release_fn+0xf0/0x360 block/blk-ioc.c:124 > process_one_work kernel/workqueue.c:2627 [inline] > process_scheduled_works+0x432/0x13f0 kernel/workqueue.c:2700 > worker_thread+0x6f2/0x1160 kernel/workqueue.c:2781 > kthread+0x33c/0x440 kernel/kthread.c:388 > ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:305 > > The buggy address belongs to the object at ffff888123839d68 > which belongs to the cache bfq_io_cq of size 1360 > The buggy address is located 336 bytes inside of > freed 1360-byte region [ffff888123839d68, ffff88812383a2b8) > > The buggy address belongs to the physical page: > page:ffffea00048e0e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88812383f588 pfn:0x123838 > head:ffffea00048e0e00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 > flags: 0x17ffffc0000a40(workingset|slab|head|node=0|zone=2|lastcpupid=0x1fffff) > page_type: 0xffffffff() > raw: 0017ffffc0000a40 ffff88810588c200 ffffea00048ffa10 ffff888105889488 > raw: ffff88812383f588 0000000000150006 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff888123839d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888123839e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >ffff888123839e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff888123839f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888123839f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > Fixes: 36eca8948323 ("block, bfq: add Early Queue Merge (EQM)") > Signed-off-by: Yu Kuai <yukuai3@huawei.com> Looks good. Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > block/bfq-iosched.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c > index 36a4998c4b37..83adac3e71db 100644 > --- a/block/bfq-iosched.c > +++ b/block/bfq-iosched.c > @@ -6934,7 +6934,8 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) > * addition, if the queue has also just been split, we have to > * resume its state. > */ > - if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) { > + if (likely(bfqq != &bfqd->oom_bfqq) && !bfqq->new_bfqq && > + bfqq_process_refs(bfqq) == 1) { > bfqq->bic = bic; > if (split) { > /* > -- > 2.39.2 >
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 36a4998c4b37..83adac3e71db 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -6934,7 +6934,8 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) * addition, if the queue has also just been split, we have to * resume its state. */ - if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) { + if (likely(bfqq != &bfqd->oom_bfqq) && !bfqq->new_bfqq && + bfqq_process_refs(bfqq) == 1) { bfqq->bic = bic; if (split) { /*