upstream boot error (2)

From: syzbot
Date: Tue Oct 30 2018 - 11:00:08 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 11743c56785c Merge tag 'rpmsg-v4.20' of git://github.com/a..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15121199400000
kernel config: https://syzkaller.appspot.com/x/.config?x=93932074d01b4a5
dashboard link: https://syzkaller.appspot.com/bug?extid=3701447012fe951dabb2
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+3701447012fe951dabb2@xxxxxxxxxxxxxxxxxxxxxxxxx

KASAN: use-after-free Read in del_timer_syncNon-volatile memory driver v1.3
Linux agpgart interface v0.103
[drm] Initialized vgem 1.0.0 20120112 for virtual device on minor 0
usbcore: registered new interface driver udl
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218
Read of size 8 at addr ffff8801d1b6b540 by task swapper/0/1

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0+ #88
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x244/0x39d lib/dump_stack.c:113
print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
__lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
del_timer_sync+0xb7/0x270 kernel/time/timer.c:1283
blk_cleanup_queue+0x413/0x710 block/blk-core.c:809
brd_free+0x5d/0x71 drivers/block/brd.c:422
brd_init+0x2eb/0x393 drivers/block/brd.c:518
do_one_initcall+0x145/0x957 init/main.c:890
do_initcall_level init/main.c:958 [inline]
do_initcalls init/main.c:966 [inline]
do_basic_setup init/main.c:984 [inline]
kernel_init_freeable+0x5c6/0x6b9 init/main.c:1148
kernel_init+0x11/0x1ae init/main.c:1068
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:350

Allocated by task 1:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
kmem_cache_alloc_node_trace+0x14c/0x740 mm/slab.c:3663
kmalloc_node include/linux/slab.h:584 [inline]
bdi_alloc_node+0x89/0xe0 mm/backing-dev.c:861
blk_alloc_queue_node+0x2b7/0xe80 block/blk-core.c:1024
blk_alloc_queue+0x1a/0x20 block/blk-core.c:911
brd_alloc+0xb9/0x540 drivers/block/brd.c:378
brd_init+0x11d/0x393 drivers/block/brd.c:498
do_one_initcall+0x145/0x957 init/main.c:890
do_initcall_level init/main.c:958 [inline]
do_initcalls init/main.c:966 [inline]
do_basic_setup init/main.c:984 [inline]
kernel_init_freeable+0x5c6/0x6b9 init/main.c:1148
kernel_init+0x11/0x1ae init/main.c:1068
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:350

Freed by task 12:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xcf/0x230 mm/slab.c:3817
release_bdi mm/backing-dev.c:968 [inline]
kref_put include/linux/kref.h:70 [inline]
bdi_put+0x138/0x180 mm/backing-dev.c:973
blk_exit_queue+0xbf/0xf0 block/blk-core.c:746
__blk_release_queue+0x12f/0x510 block/blk-sysfs.c:841
process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
kthread+0x35a/0x440 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:350

The buggy address belongs to the object at ffff8801d1b6ae80
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1728 bytes inside of
2048-byte region [ffff8801d1b6ae80, ffff8801d1b6b680)
The buggy address belongs to the page:
page:ffffea000746da80 count:1 mapcount:0 mapping:ffff8801da800c40 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea000746da08 ffffea000746dc08 ffff8801da800c40
raw: 0000000000000000 ffff8801d1b6a600 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801d1b6b400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801d1b6b480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

ffff8801d1b6b500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff8801d1b6b580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801d1b6b600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: syzbot: "KASAN: slab-out-of-bounds Read in _decode_session6 (2)"
Previous message: Steven Rostedt: "Re: [PATCH AUTOSEL 4.14 17/19] selftests: ftrace: Add synthetic event syntax testcase"
Next in thread: Ming Lei: "Re: upstream boot error (2)"
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