[syzbot] KASAN: use-after-free Read in blk_mq_sched_free_rqs

From: syzbot
Date: Tue May 03 2022 - 07:48:36 EST

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Hello,

syzbot found the following issue on:

HEAD commit: febb2d2fa561 Merge tag 'for-net-2022-04-27' of git://git.k..
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=11aaf7f0f00000
kernel config: https://syzkaller.appspot.com/x/.config?x=88991a1d8c403a9e
dashboard link: https://syzkaller.appspot.com/bug?extid=3e3f419f4a7816471838
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3e3f419f4a7816471838@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in blk_mq_sched_free_rqs+0x211/0x250 block/blk-mq-sched.c:631
Read of size 4 at addr ffff88801b996058 by task udevd/21250

CPU: 1 PID: 21250 Comm: udevd Not tainted 5.18.0-rc3-syzkaller-00277-gfebb2d2fa561 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313
print_report mm/kasan/report.c:429 [inline]
kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
blk_mq_sched_free_rqs+0x211/0x250 block/blk-mq-sched.c:631
elevator_exit+0x3b/0x70 block/elevator.c:196
disk_release_mq block/genhd.c:1139 [inline]
disk_release+0x17c/0x420 block/genhd.c:1168
device_release+0x9f/0x240 drivers/base/core.c:2229
kobject_cleanup lib/kobject.c:673 [inline]
kobject_release lib/kobject.c:704 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1c8/0x540 lib/kobject.c:721
put_device+0x1b/0x30 drivers/base/core.c:3512
blkdev_close+0x64/0x80 block/fops.c:512
__fput+0x277/0x9d0 fs/file_table.c:317
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:169 [inline]
exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:294
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f764d925fc3
Code: 48 ff ff ff b8 ff ff ff ff e9 3e ff ff ff 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8
RSP: 002b:00007fff1c213418 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f764dcee6a8 RCX: 00007f764d925fc3
RDX: 0000000003938700 RSI: 000000000aba9500 RDI: 0000000000000008
RBP: 000055ec72d9d8f0 R08: 0000000000000001 R09: 000055ec72dbc190
R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000002
R13: 000055ec72d9fb70 R14: 0000000000000008 R15: 000055ec72d96910
</TASK>

Allocated by task 1:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
kmalloc include/linux/slab.h:581 [inline]
kzalloc include/linux/slab.h:714 [inline]
nbd_dev_add+0x4d/0xcd0 drivers/block/nbd.c:1730
nbd_init+0x297/0x2a7 drivers/block/nbd.c:2511
do_one_initcall+0x103/0x650 init/main.c:1298
do_initcall_level init/main.c:1371 [inline]
do_initcalls init/main.c:1387 [inline]
do_basic_setup init/main.c:1406 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1613
kernel_init+0x1a/0x1d0 init/main.c:1502
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

Freed by task 8:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0x166/0x1a0 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1728 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754
slab_free mm/slub.c:3510 [inline]
kfree+0xd6/0x4d0 mm/slub.c:4552
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

Last potentially related work creation:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
__kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
insert_work+0x48/0x350 kernel/workqueue.c:1358
__queue_work+0x62e/0x1140 kernel/workqueue.c:1517
queue_work_on+0xee/0x110 kernel/workqueue.c:1545
queue_work include/linux/workqueue.h:502 [inline]
nbd_put drivers/block/nbd.c:279 [inline]
nbd_put+0xd7/0x120 drivers/block/nbd.c:272
blkdev_put_whole block/bdev.c:689 [inline]
blkdev_put+0x2e4/0x950 block/bdev.c:947
blkdev_close+0x64/0x80 block/fops.c:512
__fput+0x277/0x9d0 fs/file_table.c:317
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:169 [inline]
exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:294
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88801b996000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 88 bytes inside of
1024-byte region [ffff88801b996000, ffff88801b996400)

The buggy address belongs to the physical page:
page:ffffea00006e6400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1b990
head:ffffea00006e6400 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888010c41dc0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 7498210050, free_ts 0
prep_new_page mm/page_alloc.c:2441 [inline]
get_page_from_freelist+0xba2/0x3e00 mm/page_alloc.c:4182
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5408
__alloc_pages_node include/linux/gfp.h:587 [inline]
alloc_slab_page mm/slub.c:1801 [inline]
allocate_slab+0x80/0x3c0 mm/slub.c:1944
new_slab mm/slub.c:2004 [inline]
___slab_alloc+0x8df/0xf20 mm/slub.c:3005
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3092
slab_alloc_node mm/slub.c:3183 [inline]
kmem_cache_alloc_node_trace+0x116/0x310 mm/slub.c:3281
kmalloc_node include/linux/slab.h:599 [inline]
kzalloc_node include/linux/slab.h:725 [inline]
sbitmap_queue_init_node+0x1d8/0x460 lib/sbitmap.c:438
bt_alloc block/blk-mq-tag.c:543 [inline]
blk_mq_init_bitmaps+0x57/0x180 block/blk-mq-tag.c:555
blk_mq_init_tags+0x10b/0x170 block/blk-mq-tag.c:586
blk_mq_alloc_rq_map+0x1ba/0x3b0 block/blk-mq.c:3169
blk_mq_alloc_map_and_rqs block/blk-mq.c:3620 [inline]
__blk_mq_alloc_map_and_rqs block/blk-mq.c:3642 [inline]
__blk_mq_alloc_map_and_rqs block/blk-mq.c:3633 [inline]
__blk_mq_alloc_rq_maps block/blk-mq.c:4119 [inline]
blk_mq_alloc_set_map_and_rqs block/blk-mq.c:4150 [inline]
blk_mq_alloc_tag_set+0x8cc/0x12b0 block/blk-mq.c:4309
nbd_dev_add+0x2b1/0xcd0 drivers/block/nbd.c:1745
nbd_init+0x297/0x2a7 drivers/block/nbd.c:2511
do_one_initcall+0x103/0x650 init/main.c:1298
do_initcall_level init/main.c:1371 [inline]
do_initcalls init/main.c:1387 [inline]
do_basic_setup init/main.c:1406 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1613
kernel_init+0x1a/0x1d0 init/main.c:1502
page_owner free stack trace missing

Memory state around the buggy address:
ffff88801b995f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88801b995f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801b996000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88801b996080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88801b996100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: Dmitry Vyukov: "Re: [syzbot] WARNING in cpuset_write_resmask"
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