* [PATCH AUTOSEL 5.4 04/16] block, bfq: don't move oom_bfqq
[not found] <20220328112345.1556601-1-sashal@kernel.org>
@ 2022-03-28 11:23 ` Sasha Levin
2022-03-28 11:23 ` [PATCH AUTOSEL 5.4 06/16] loop: use sysfs_emit() in the sysfs xxx show() Sasha Levin
` (2 subsequent siblings)
3 siblings, 0 replies; 4+ messages in thread
From: Sasha Levin @ 2022-03-28 11:23 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Yu Kuai, Jan Kara, Paolo Valente, Jens Axboe, Sasha Levin, tj,
cgroups, linux-block
From: Yu Kuai <yukuai3@huawei.com>
[ Upstream commit 8410f70977734f21b8ed45c37e925d311dfda2e7 ]
Our test report a UAF:
[ 2073.019181] ==================================================================
[ 2073.019188] BUG: KASAN: use-after-free in __bfq_put_async_bfqq+0xa0/0x168
[ 2073.019191] Write of size 8 at addr ffff8000ccf64128 by task rmmod/72584
[ 2073.019192]
[ 2073.019196] CPU: 0 PID: 72584 Comm: rmmod Kdump: loaded Not tainted 4.19.90-yk #5
[ 2073.019198] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
[ 2073.019200] Call trace:
[ 2073.019203] dump_backtrace+0x0/0x310
[ 2073.019206] show_stack+0x28/0x38
[ 2073.019210] dump_stack+0xec/0x15c
[ 2073.019216] print_address_description+0x68/0x2d0
[ 2073.019220] kasan_report+0x238/0x2f0
[ 2073.019224] __asan_store8+0x88/0xb0
[ 2073.019229] __bfq_put_async_bfqq+0xa0/0x168
[ 2073.019233] bfq_put_async_queues+0xbc/0x208
[ 2073.019236] bfq_pd_offline+0x178/0x238
[ 2073.019240] blkcg_deactivate_policy+0x1f0/0x420
[ 2073.019244] bfq_exit_queue+0x128/0x178
[ 2073.019249] blk_mq_exit_sched+0x12c/0x160
[ 2073.019252] elevator_exit+0xc8/0xd0
[ 2073.019256] blk_exit_queue+0x50/0x88
[ 2073.019259] blk_cleanup_queue+0x228/0x3d8
[ 2073.019267] null_del_dev+0xfc/0x1e0 [null_blk]
[ 2073.019274] null_exit+0x90/0x114 [null_blk]
[ 2073.019278] __arm64_sys_delete_module+0x358/0x5a0
[ 2073.019282] el0_svc_common+0xc8/0x320
[ 2073.019287] el0_svc_handler+0xf8/0x160
[ 2073.019290] el0_svc+0x10/0x218
[ 2073.019291]
[ 2073.019294] Allocated by task 14163:
[ 2073.019301] kasan_kmalloc+0xe0/0x190
[ 2073.019305] kmem_cache_alloc_node_trace+0x1cc/0x418
[ 2073.019308] bfq_pd_alloc+0x54/0x118
[ 2073.019313] blkcg_activate_policy+0x250/0x460
[ 2073.019317] bfq_create_group_hierarchy+0x38/0x110
[ 2073.019321] bfq_init_queue+0x6d0/0x948
[ 2073.019325] blk_mq_init_sched+0x1d8/0x390
[ 2073.019330] elevator_switch_mq+0x88/0x170
[ 2073.019334] elevator_switch+0x140/0x270
[ 2073.019338] elv_iosched_store+0x1a4/0x2a0
[ 2073.019342] queue_attr_store+0x90/0xe0
[ 2073.019348] sysfs_kf_write+0xa8/0xe8
[ 2073.019351] kernfs_fop_write+0x1f8/0x378
[ 2073.019359] __vfs_write+0xe0/0x360
[ 2073.019363] vfs_write+0xf0/0x270
[ 2073.019367] ksys_write+0xdc/0x1b8
[ 2073.019371] __arm64_sys_write+0x50/0x60
[ 2073.019375] el0_svc_common+0xc8/0x320
[ 2073.019380] el0_svc_handler+0xf8/0x160
[ 2073.019383] el0_svc+0x10/0x218
[ 2073.019385]
[ 2073.019387] Freed by task 72584:
[ 2073.019391] __kasan_slab_free+0x120/0x228
[ 2073.019394] kasan_slab_free+0x10/0x18
[ 2073.019397] kfree+0x94/0x368
[ 2073.019400] bfqg_put+0x64/0xb0
[ 2073.019404] bfqg_and_blkg_put+0x90/0xb0
[ 2073.019408] bfq_put_queue+0x220/0x228
[ 2073.019413] __bfq_put_async_bfqq+0x98/0x168
[ 2073.019416] bfq_put_async_queues+0xbc/0x208
[ 2073.019420] bfq_pd_offline+0x178/0x238
[ 2073.019424] blkcg_deactivate_policy+0x1f0/0x420
[ 2073.019429] bfq_exit_queue+0x128/0x178
[ 2073.019433] blk_mq_exit_sched+0x12c/0x160
[ 2073.019437] elevator_exit+0xc8/0xd0
[ 2073.019440] blk_exit_queue+0x50/0x88
[ 2073.019443] blk_cleanup_queue+0x228/0x3d8
[ 2073.019451] null_del_dev+0xfc/0x1e0 [null_blk]
[ 2073.019459] null_exit+0x90/0x114 [null_blk]
[ 2073.019462] __arm64_sys_delete_module+0x358/0x5a0
[ 2073.019467] el0_svc_common+0xc8/0x320
[ 2073.019471] el0_svc_handler+0xf8/0x160
[ 2073.019474] el0_svc+0x10/0x218
[ 2073.019475]
[ 2073.019479] The buggy address belongs to the object at ffff8000ccf63f00
which belongs to the cache kmalloc-1024 of size 1024
[ 2073.019484] The buggy address is located 552 bytes inside of
1024-byte region [ffff8000ccf63f00, ffff8000ccf64300)
[ 2073.019486] The buggy address belongs to the page:
[ 2073.019492] page:ffff7e000333d800 count:1 mapcount:0 mapping:ffff8000c0003a00 index:0x0 compound_mapcount: 0
[ 2073.020123] flags: 0x7ffff0000008100(slab|head)
[ 2073.020403] raw: 07ffff0000008100 ffff7e0003334c08 ffff7e00001f5a08 ffff8000c0003a00
[ 2073.020409] raw: 0000000000000000 00000000001c001c 00000001ffffffff 0000000000000000
[ 2073.020411] page dumped because: kasan: bad access detected
[ 2073.020412]
[ 2073.020414] Memory state around the buggy address:
[ 2073.020420] ffff8000ccf64000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2073.020424] ffff8000ccf64080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2073.020428] >ffff8000ccf64100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2073.020430] ^
[ 2073.020434] ffff8000ccf64180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2073.020438] ffff8000ccf64200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2073.020439] ==================================================================
The same problem exist in mainline as well.
This is because oom_bfqq is moved to a non-root group, thus root_group
is freed earlier.
Thus fix the problem by don't move oom_bfqq.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Link: https://lore.kernel.org/r/20220129015924.3958918-4-yukuai3@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
block/bfq-cgroup.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 342a1cfa48c5..c17eb794f0ae 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -625,6 +625,12 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
{
struct bfq_entity *entity = &bfqq->entity;
+ /*
+ * oom_bfqq is not allowed to move, oom_bfqq will hold ref to root_group
+ * until elevator exit.
+ */
+ if (bfqq == &bfqd->oom_bfqq)
+ return;
/*
* Get extra reference to prevent bfqq from being freed in
* next possible expire or deactivate.
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH AUTOSEL 5.4 06/16] loop: use sysfs_emit() in the sysfs xxx show()
[not found] <20220328112345.1556601-1-sashal@kernel.org>
2022-03-28 11:23 ` [PATCH AUTOSEL 5.4 04/16] block, bfq: don't move oom_bfqq Sasha Levin
@ 2022-03-28 11:23 ` Sasha Levin
2022-03-28 11:23 ` [PATCH AUTOSEL 5.4 10/16] bfq: fix use-after-free in bfq_dispatch_request Sasha Levin
2022-03-28 11:23 ` [PATCH AUTOSEL 5.4 13/16] Revert "Revert "block, bfq: honor already-setup queue merges"" Sasha Levin
3 siblings, 0 replies; 4+ messages in thread
From: Sasha Levin @ 2022-03-28 11:23 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Chaitanya Kulkarni, Himanshu Madhani, Jens Axboe, Sasha Levin,
linux-block
From: Chaitanya Kulkarni <kch@nvidia.com>
[ Upstream commit b27824d31f09ea7b4a6ba2c1b18bd328df3e8bed ]
sprintf does not know the PAGE_SIZE maximum of the temporary buffer
used for outputting sysfs content and it's possible to overrun the
PAGE_SIZE buffer length.
Use a generic sysfs_emit function that knows the size of the
temporary buffer and ensures that no overrun is done for offset
attribute in
loop_attr_[offset|sizelimit|autoclear|partscan|dio]_show() callbacks.
Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Link: https://lore.kernel.org/r/20220215213310.7264-2-kch@nvidia.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/loop.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index ffbe792410d1..6b3e27b8cd24 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -794,33 +794,33 @@ static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
{
- return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
+ return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
}
static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
{
- return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
+ return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
}
static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
{
int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
- return sprintf(buf, "%s\n", autoclear ? "1" : "0");
+ return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0");
}
static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
{
int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
- return sprintf(buf, "%s\n", partscan ? "1" : "0");
+ return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
}
static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
{
int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
- return sprintf(buf, "%s\n", dio ? "1" : "0");
+ return sysfs_emit(buf, "%s\n", dio ? "1" : "0");
}
LOOP_ATTR_RO(backing_file);
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH AUTOSEL 5.4 10/16] bfq: fix use-after-free in bfq_dispatch_request
[not found] <20220328112345.1556601-1-sashal@kernel.org>
2022-03-28 11:23 ` [PATCH AUTOSEL 5.4 04/16] block, bfq: don't move oom_bfqq Sasha Levin
2022-03-28 11:23 ` [PATCH AUTOSEL 5.4 06/16] loop: use sysfs_emit() in the sysfs xxx show() Sasha Levin
@ 2022-03-28 11:23 ` Sasha Levin
2022-03-28 11:23 ` [PATCH AUTOSEL 5.4 13/16] Revert "Revert "block, bfq: honor already-setup queue merges"" Sasha Levin
3 siblings, 0 replies; 4+ messages in thread
From: Sasha Levin @ 2022-03-28 11:23 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Zhang Wensheng, Hulk Robot, Jens Axboe, Sasha Levin,
paolo.valente, linux-block
From: Zhang Wensheng <zhangwensheng5@huawei.com>
[ Upstream commit ab552fcb17cc9e4afe0e4ac4df95fc7b30e8490a ]
KASAN reports a use-after-free report when doing normal scsi-mq test
[69832.239032] ==================================================================
[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] ==================================================================
In bfq_dispatch_requestfunction, it may have function call:
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;
Fix the problem by check in_serv_queue == 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 or finished, the idle_timer_disabled
will be false which would not give effects to bfq_update_dispatch_stats.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Wensheng <zhangwensheng5@huawei.com>
Link: https://lore.kernel.org/r/20220303070334.3020168-1-zhangwensheng5@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
block/bfq-iosched.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 1a0c581512f2..38c39d50ae04 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -4793,7 +4793,7 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
struct bfq_data *bfqd = 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 = false;
spin_lock_irq(&bfqd->lock);
@@ -4801,14 +4801,15 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue);
rq = __bfq_dispatch_request(hctx);
-
- idle_timer_disabled =
- waiting_rq && !bfq_bfqq_wait_request(in_serv_queue);
+ if (in_serv_queue == bfqd->in_service_queue) {
+ idle_timer_disabled =
+ waiting_rq && !bfq_bfqq_wait_request(in_serv_queue);
+ }
spin_unlock_irq(&bfqd->lock);
-
- bfq_update_dispatch_stats(hctx->queue, rq, in_serv_queue,
- idle_timer_disabled);
+ bfq_update_dispatch_stats(hctx->queue, rq,
+ idle_timer_disabled ? in_serv_queue : NULL,
+ idle_timer_disabled);
return rq;
}
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH AUTOSEL 5.4 13/16] Revert "Revert "block, bfq: honor already-setup queue merges""
[not found] <20220328112345.1556601-1-sashal@kernel.org>
` (2 preceding siblings ...)
2022-03-28 11:23 ` [PATCH AUTOSEL 5.4 10/16] bfq: fix use-after-free in bfq_dispatch_request Sasha Levin
@ 2022-03-28 11:23 ` Sasha Levin
3 siblings, 0 replies; 4+ messages in thread
From: Sasha Levin @ 2022-03-28 11:23 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Paolo Valente, Holger Hoffstätte, Jens Axboe, Sasha Levin,
linux-block
From: Paolo Valente <paolo.valente@linaro.org>
[ Upstream commit 15729ff8143f8135b03988a100a19e66d7cb7ecd ]
A crash [1] happened to be triggered in conjunction with commit
2d52c58b9c9b ("block, bfq: honor already-setup queue merges"). The
latter was then reverted by commit ebc69e897e17 ("Revert "block, bfq:
honor already-setup queue merges""). Yet, the reverted commit was not
the one introducing the bug. In fact, it actually triggered a UAF
introduced by a different commit, and now fixed by commit d29bd41428cf
("block, bfq: reset last_bfqq_created on group change").
So, there is no point in keeping commit 2d52c58b9c9b ("block, bfq:
honor already-setup queue merges") out. This commit restores it.
[1] https://bugzilla.kernel.org/show_bug.cgi?id=214503
Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Link: https://lore.kernel.org/r/20211125181510.15004-1-paolo.valente@linaro.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
block/bfq-iosched.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 38c39d50ae04..1d443d17cf7c 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2523,6 +2523,15 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
* are likely to increase the throughput.
*/
bfqq->new_bfqq = new_bfqq;
+ /*
+ * The above assignment schedules the following redirections:
+ * each time some I/O for bfqq arrives, the process that
+ * generated that I/O is disassociated from bfqq and
+ * associated with new_bfqq. Here we increases new_bfqq->ref
+ * in advance, adding the number of processes that are
+ * expected to be associated with new_bfqq as they happen to
+ * issue I/O.
+ */
new_bfqq->ref += process_refs;
return new_bfqq;
}
@@ -2582,6 +2591,10 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
{
struct bfq_queue *in_service_bfqq, *new_bfqq;
+ /* if a merge has already been setup, then proceed with that first */
+ if (bfqq->new_bfqq)
+ return bfqq->new_bfqq;
+
/*
* Do not perform queue merging if the device is non
* rotational and performs internal queueing. In fact, such a
@@ -2636,9 +2649,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
if (bfq_too_late_for_merging(bfqq))
return NULL;
- if (bfqq->new_bfqq)
- return bfqq->new_bfqq;
-
if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
return NULL;
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread