KASAN: use-after-free Read in __io_req_task_submit

From: syzbot
Date: Tue Aug 11 2020 - 22:16:35 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 00e4db51 Merge tag 'perf-tools-2020-08-10' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13829022900000
kernel config: https://syzkaller.appspot.com/x/.config?x=64a3282e09356140
dashboard link: https://syzkaller.appspot.com/bug?extid=3c72ce3136524268d7af
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1612cee2900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14e3b1b2900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3c72ce3136524268d7af@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:56 [inline]
BUG: KASAN: use-after-free in atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline]
BUG: KASAN: use-after-free in atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
BUG: KASAN: use-after-free in __mutex_unlock_slowpath+0x8e/0x610 kernel/locking/mutex.c:1237
Read of size 8 at addr ffff88809de9c3c0 by task syz-executor338/1394

CPU: 1 PID: 1394 Comm: syz-executor338 Not tainted 5.8.0-syzkaller #0
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+0x18f/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
check_memory_region_inline mm/kasan/generic.c:186 [inline]
check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
instrument_atomic_read include/linux/instrumented.h:56 [inline]
atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline]
atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
__mutex_unlock_slowpath+0x8e/0x610 kernel/locking/mutex.c:1237
__io_req_task_submit+0x8a/0xe0 fs/io_uring.c:1760
task_work_run+0xdd/0x190 kernel/task_work.c:135
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:139 [inline]
exit_to_user_mode_prepare+0x1aa/0x1d0 kernel/entry/common.c:166
syscall_exit_to_user_mode+0x59/0x2b0 kernel/entry/common.c:241
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x449b99
Code: e8 3c e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4c0bec2cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 00000000006e5a38 RCX: 0000000000449b99
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006e5a38
RBP: 00000000006e5a30 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e5a3c
R13: 00007ffdb6e3600f R14: 00007f4c0bec39c0 R15: 20c49ba5e353f7cf

Allocated by task 1347:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
kmem_cache_alloc_trace+0x16e/0x2c0 mm/slab.c:3550
kmalloc include/linux/slab.h:554 [inline]
kzalloc include/linux/slab.h:666 [inline]
io_ring_ctx_alloc fs/io_uring.c:1030 [inline]
io_uring_create fs/io_uring.c:8308 [inline]
io_uring_setup+0x4df/0x28c0 fs/io_uring.c:8401
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6838:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
__kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
__cache_free mm/slab.c:3418 [inline]
kfree+0x103/0x2c0 mm/slab.c:3756
process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Last call_rcu():
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_record_aux_stack+0x82/0xb0 mm/kasan/generic.c:346
__call_rcu kernel/rcu/tree.c:2894 [inline]
call_rcu+0x14f/0x7e0 kernel/rcu/tree.c:2968
__percpu_ref_switch_to_atomic lib/percpu-refcount.c:192 [inline]
__percpu_ref_switch_mode+0x365/0x700 lib/percpu-refcount.c:237
percpu_ref_kill_and_confirm+0x94/0x350 lib/percpu-refcount.c:350
percpu_ref_kill include/linux/percpu-refcount.h:136 [inline]
io_ring_ctx_wait_and_kill+0x38/0x600 fs/io_uring.c:7797
io_uring_release+0x3e/0x50 fs/io_uring.c:7829
__fput+0x285/0x920 fs/file_table.c:281
task_work_run+0xdd/0x190 kernel/task_work.c:135
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:139 [inline]
exit_to_user_mode_prepare+0x1aa/0x1d0 kernel/entry/common.c:166
syscall_exit_to_user_mode+0x59/0x2b0 kernel/entry/common.c:241
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Second to last call_rcu():
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_record_aux_stack+0x82/0xb0 mm/kasan/generic.c:346
__call_rcu kernel/rcu/tree.c:2894 [inline]
call_rcu+0x14f/0x7e0 kernel/rcu/tree.c:2968
__percpu_ref_switch_to_atomic lib/percpu-refcount.c:192 [inline]
__percpu_ref_switch_mode+0x365/0x700 lib/percpu-refcount.c:237
percpu_ref_kill_and_confirm+0x94/0x350 lib/percpu-refcount.c:350
percpu_ref_kill include/linux/percpu-refcount.h:136 [inline]
io_ring_ctx_wait_and_kill+0x38/0x600 fs/io_uring.c:7797
io_uring_release+0x3e/0x50 fs/io_uring.c:7829
__fput+0x285/0x920 fs/file_table.c:281
task_work_run+0xdd/0x190 kernel/task_work.c:135
exit_task_work include/linux/task_work.h:25 [inline]
do_exit+0xb7d/0x29f0 kernel/exit.c:806
do_group_exit+0x125/0x310 kernel/exit.c:903
get_signal+0x40b/0x1ee0 kernel/signal.c:2743
arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811
exit_to_user_mode_loop kernel/entry/common.c:135 [inline]
exit_to_user_mode_prepare+0x172/0x1d0 kernel/entry/common.c:166
syscall_exit_to_user_mode+0x59/0x2b0 kernel/entry/common.c:241
entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88809de9c000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 960 bytes inside of
2048-byte region [ffff88809de9c000, ffff88809de9c800)
The buggy address belongs to the page:
page:00000000f914c910 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9de9c
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002422c08 ffffea0002765948 ffff8880aa040800
raw: 0000000000000000 ffff88809de9c000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809de9c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809de9c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809de9c380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809de9c400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809de9c480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: Peter Chen: "Re: [RFC v4 1/3] usb: dwc3: Resize TX FIFOs to meet EP bursting requirements"
Previous message: Jason Wang: "Re: VDPA Debug/Statistics"
Next in thread: Jens Axboe: "Re: KASAN: use-after-free Read in __io_req_task_submit"
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