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[93.70.85.238]) by smtp.gmail.com with ESMTPSA id ga42sm1954318ejc.200.2021.12.16.08.27.30 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 Dec 2021 08:27:31 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) Subject: Re: [PATCH -next v3] bfq: fix use-after-free in bfq_dispatch_request From: Paolo Valente In-Reply-To: <20211216122157.672159-1-zhangwensheng5@huawei.com> Date: Thu, 16 Dec 2021 17:27:30 +0100 Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <42FD69CD-16CF-447D-AA69-621EE97CE3DC@linaro.org> References: <20211216122157.672159-1-zhangwensheng5@huawei.com> To: Zhang Wensheng X-Mailer: Apple Mail (2.3445.104.11) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Il giorno 16 dic 2021, alle ore 13:21, Zhang Wensheng = ha scritto: >=20 > KASAN reports a use-after-free report when doing normal scsi-mq test >=20 > [69832.239032] = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > [69832.241810] BUG: KASAN: use-after-free in = bfq_dispatch_request+0x1045/0x44b0 > [69832.243267] Read of size 8 at addr ffff88802622ba88 by task = kworker/3:1H/155 > [69832.244656] > [69832.245007] CPU: 3 PID: 155 Comm: kworker/3:1H Not tainted = 5.10.0-10295-g576c6382529e #8 > [69832.246626] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), = BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > [69832.249069] Workqueue: kblockd blk_mq_run_work_fn > [69832.250022] Call Trace: > [69832.250541] dump_stack+0x9b/0xce > [69832.251232] ? bfq_dispatch_request+0x1045/0x44b0 > [69832.252243] print_address_description.constprop.6+0x3e/0x60 > [69832.253381] ? __cpuidle_text_end+0x5/0x5 > [69832.254211] ? vprintk_func+0x6b/0x120 > [69832.254994] ? bfq_dispatch_request+0x1045/0x44b0 > [69832.255952] ? bfq_dispatch_request+0x1045/0x44b0 > [69832.256914] kasan_report.cold.9+0x22/0x3a > [69832.257753] ? bfq_dispatch_request+0x1045/0x44b0 > [69832.258755] check_memory_region+0x1c1/0x1e0 > [69832.260248] bfq_dispatch_request+0x1045/0x44b0 > [69832.261181] ? bfq_bfqq_expire+0x2440/0x2440 > [69832.262032] ? blk_mq_delay_run_hw_queues+0xf9/0x170 > [69832.263022] __blk_mq_do_dispatch_sched+0x52f/0x830 > [69832.264011] ? blk_mq_sched_request_inserted+0x100/0x100 > [69832.265101] __blk_mq_sched_dispatch_requests+0x398/0x4f0 > [69832.266206] ? blk_mq_do_dispatch_ctx+0x570/0x570 > [69832.267147] ? __switch_to+0x5f4/0xee0 > [69832.267898] blk_mq_sched_dispatch_requests+0xdf/0x140 > [69832.268946] __blk_mq_run_hw_queue+0xc0/0x270 > [69832.269840] blk_mq_run_work_fn+0x51/0x60 > [69832.278170] process_one_work+0x6d4/0xfe0 > [69832.278984] worker_thread+0x91/0xc80 > [69832.279726] ? __kthread_parkme+0xb0/0x110 > [69832.280554] ? process_one_work+0xfe0/0xfe0 > [69832.281414] kthread+0x32d/0x3f0 > [69832.282082] ? kthread_park+0x170/0x170 > [69832.282849] ret_from_fork+0x1f/0x30 > [69832.283573] > [69832.283886] Allocated by task 7725: > [69832.284599] kasan_save_stack+0x19/0x40 > [69832.285385] __kasan_kmalloc.constprop.2+0xc1/0xd0 > [69832.286350] kmem_cache_alloc_node+0x13f/0x460 > [69832.287237] bfq_get_queue+0x3d4/0x1140 > [69832.287993] bfq_get_bfqq_handle_split+0x103/0x510 > [69832.289015] bfq_init_rq+0x337/0x2d50 > [69832.289749] bfq_insert_requests+0x304/0x4e10 > [69832.290634] blk_mq_sched_insert_requests+0x13e/0x390 > [69832.291629] blk_mq_flush_plug_list+0x4b4/0x760 > [69832.292538] blk_flush_plug_list+0x2c5/0x480 > [69832.293392] io_schedule_prepare+0xb2/0xd0 > [69832.294209] io_schedule_timeout+0x13/0x80 > [69832.295014] wait_for_common_io.constprop.1+0x13c/0x270 > [69832.296137] submit_bio_wait+0x103/0x1a0 > [69832.296932] blkdev_issue_discard+0xe6/0x160 > [69832.297794] blk_ioctl_discard+0x219/0x290 > [69832.298614] blkdev_common_ioctl+0x50a/0x1750 > [69832.304715] blkdev_ioctl+0x470/0x600 > [69832.305474] block_ioctl+0xde/0x120 > [69832.306232] vfs_ioctl+0x6c/0xc0 > [69832.306877] __se_sys_ioctl+0x90/0xa0 > [69832.307629] do_syscall_64+0x2d/0x40 > [69832.308362] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [69832.309382] > [69832.309701] Freed by task 155: > [69832.310328] kasan_save_stack+0x19/0x40 > [69832.311121] kasan_set_track+0x1c/0x30 > [69832.311868] kasan_set_free_info+0x1b/0x30 > [69832.312699] __kasan_slab_free+0x111/0x160 > [69832.313524] kmem_cache_free+0x94/0x460 > [69832.314367] bfq_put_queue+0x582/0x940 > [69832.315112] __bfq_bfqd_reset_in_service+0x166/0x1d0 > [69832.317275] bfq_bfqq_expire+0xb27/0x2440 > [69832.318084] bfq_dispatch_request+0x697/0x44b0 > [69832.318991] __blk_mq_do_dispatch_sched+0x52f/0x830 > [69832.319984] __blk_mq_sched_dispatch_requests+0x398/0x4f0 > [69832.321087] blk_mq_sched_dispatch_requests+0xdf/0x140 > [69832.322225] __blk_mq_run_hw_queue+0xc0/0x270 > [69832.323114] blk_mq_run_work_fn+0x51/0x60 > [69832.323942] process_one_work+0x6d4/0xfe0 > [69832.324772] worker_thread+0x91/0xc80 > [69832.325518] kthread+0x32d/0x3f0 > [69832.326205] ret_from_fork+0x1f/0x30 > [69832.326932] > [69832.338297] The buggy address belongs to the object at = ffff88802622b968 > [69832.338297] which belongs to the cache bfq_queue of size 512 > [69832.340766] The buggy address is located 288 bytes inside of > [69832.340766] 512-byte region [ffff88802622b968, ffff88802622bb68) > [69832.343091] The buggy address belongs to the page: > [69832.344097] page:ffffea0000988a00 refcount:1 mapcount:0 = mapping:0000000000000000 index:0xffff88802622a528 pfn:0x26228 > [69832.346214] head:ffffea0000988a00 order:2 compound_mapcount:0 = compound_pincount:0 > [69832.347719] flags: 0x1fffff80010200(slab|head) > [69832.348625] raw: 001fffff80010200 ffffea0000dbac08 ffff888017a57650 = ffff8880179fe840 > [69832.354972] raw: ffff88802622a528 0000000000120008 00000001ffffffff = 0000000000000000 > [69832.356547] page dumped because: kasan: bad access detected > [69832.357652] > [69832.357970] Memory state around the buggy address: > [69832.358926] ffff88802622b980: fb fb fb fb fb fb fb fb fb fb fb fb = fb fb fb fb > [69832.360358] ffff88802622ba00: fb fb fb fb fb fb fb fb fb fb fb fb = fb fb fb fb > [69832.361810] >ffff88802622ba80: fb fb fb fb fb fb fb fb fb fb fb fb = fb fb fb fb > [69832.363273] ^ > [69832.363975] ffff88802622bb00: fb fb fb fb fb fb fb fb fb fb fb fb = fb fc fc fc > [69832.375960] ffff88802622bb80: fc fc fc fc fc fc fc fc fc fc fc fc = fc fc fc fc > [69832.377405] = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >=20 > In bfq_dispatch_requestfunction, it may have function call: >=20 > bfq_dispatch_request > __bfq_dispatch_request > bfq_select_queue > bfq_bfqq_expire > __bfq_bfqd_reset_in_service > bfq_put_queue > kmem_cache_free > In this function call, in_serv_queue has beed expired and meet > the conditions to free. In the function bfq_dispatch_request, > the address of in_serv_queue pointing to has been released. For > getting the value of idle_timer_disabled, it will get flags > value from the address which in_serv_queue pointing to, then > the problem of use-after-free happens; >=20 > Fix the problem by check in_serv_queue =3D=3D bfqd->in_service_queue, > to get the value of idle_timer_disabled if in_serve_queue is equel > to bfqd->in_service_queue. If the space of in_serv_queue pointing > has been released, this judge will aviod use-after-free problem. > And if in_serv_queue may be expired but it still exists, this judge > may have little effects on the function bfqg_stats_update_idle_time > in bfq_update_dispatch_stats. >=20 > Reported-by: Hulk Robot > Signed-off-by: Zhang Wensheng > --- > block/bfq-iosched.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) >=20 > diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c > index fec18118dc30..97533634b99e 100644 > --- a/block/bfq-iosched.c > +++ b/block/bfq-iosched.c > @@ -5061,7 +5061,7 @@ static struct request = *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx) > struct bfq_data *bfqd =3D hctx->queue->elevator->elevator_data; > struct request *rq; > struct bfq_queue *in_serv_queue; > - bool waiting_rq, idle_timer_disabled; > + bool waiting_rq, idle_timer_disabled =3D false; >=20 > spin_lock_irq(&bfqd->lock); >=20 > @@ -5070,9 +5070,10 @@ static struct request = *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx) >=20 > rq =3D __bfq_dispatch_request(hctx); >=20 > - idle_timer_disabled =3D > - waiting_rq && !bfq_bfqq_wait_request(in_serv_queue); > - > + if (in_serv_queue =3D=3D bfqd->in_service_queue) { > + idle_timer_disabled =3D > + waiting_rq && = !bfq_bfqq_wait_request(in_serv_queue); > + } Good catch! > spin_unlock_irq(&bfqd->lock); >=20 > bfq_update_dispatch_stats(hctx->queue, rq, in_serv_queue, Yet, what about the above use of in_serv_queue then? Thanks, Paolo > --=20 > 2.31.1 >=20