KASAN: null-ptr-deref Write in bdi_put
From: syzbot
Date: Wed Dec 09 2020 - 04:04:54 EST
Hello,
syzbot found the following issue on:
HEAD commit: 15ac8fdb Add linux-next specific files for 20201207
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1735927b500000
kernel config: https://syzkaller.appspot.com/x/.config?x=3696b8138207d24d
dashboard link: https://syzkaller.appspot.com/bug?extid=aded2f2ab94d81727898
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11993623500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15799413500000
The issue was bisected to:
commit 4d004099a668c41522242aa146a38cc4eb59cb1e
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Fri Oct 2 09:04:21 2020 +0000
lockdep: Fix lockdep recursion
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1469d00f500000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1669d00f500000
console output: https://syzkaller.appspot.com/x/log.txt?x=1269d00f500000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aded2f2ab94d81727898@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 4d004099a668 ("lockdep: Fix lockdep recursion")
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: null-ptr-deref in atomic_fetch_sub_release include/asm-generic/atomic-instrumented.h:220 [inline]
BUG: KASAN: null-ptr-deref in __refcount_sub_and_test include/linux/refcount.h:272 [inline]
BUG: KASAN: null-ptr-deref in __refcount_dec_and_test include/linux/refcount.h:315 [inline]
BUG: KASAN: null-ptr-deref in refcount_dec_and_test include/linux/refcount.h:333 [inline]
BUG: KASAN: null-ptr-deref in kref_put include/linux/kref.h:64 [inline]
BUG: KASAN: null-ptr-deref in bdi_put+0x22/0xa0 mm/backing-dev.c:901
Write of size 4 at addr 0000000000000040 by task syz-executor719/8459
CPU: 1 PID: 8459 Comm: syz-executor719 Not tainted 5.10.0-rc6-next-20201207-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
__kasan_report mm/kasan/report.c:400 [inline]
kasan_report.cold+0x5f/0xd5 mm/kasan/report.c:413
check_memory_region_inline mm/kasan/generic.c:180 [inline]
check_memory_region+0x13d/0x180 mm/kasan/generic.c:186
instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
atomic_fetch_sub_release include/asm-generic/atomic-instrumented.h:220 [inline]
__refcount_sub_and_test include/linux/refcount.h:272 [inline]
__refcount_dec_and_test include/linux/refcount.h:315 [inline]
refcount_dec_and_test include/linux/refcount.h:333 [inline]
kref_put include/linux/kref.h:64 [inline]
bdi_put+0x22/0xa0 mm/backing-dev.c:901
bdev_evict_inode+0x280/0x4a0 fs/block_dev.c:809
evict+0x2ed/0x6b0 fs/inode.c:577
iput_final fs/inode.c:1651 [inline]
iput.part.0+0x41e/0x840 fs/inode.c:1677
iput+0x58/0x70 fs/inode.c:1667
dentry_unlink_inode+0x2b1/0x3d0 fs/dcache.c:374
__dentry_kill+0x3c0/0x640 fs/dcache.c:579
dentry_kill fs/dcache.c:705 [inline]
dput+0x786/0xc10 fs/dcache.c:878
do_one_tree fs/dcache.c:1625 [inline]
shrink_dcache_for_umount+0x11f/0x330 fs/dcache.c:1639
generic_shutdown_super+0x68/0x370 fs/super.c:447
kill_anon_super+0x36/0x60 fs/super.c:1055
deactivate_locked_super+0x94/0x160 fs/super.c:335
deactivate_super+0xad/0xd0 fs/super.c:366
cleanup_mnt+0x3a3/0x530 fs/namespace.c:1123
task_work_run+0xdd/0x190 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x1f0/0x200 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x444439
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 db d7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc4e2a8a38 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffea RBX: 00007ffc4e2a8a40 RCX: 0000000000444439
RDX: 0000000020000100 RSI: 00000000200000c0 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000400c60
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004020a0
R13: 0000000000402130 R14: 0000000000000000 R15: 0000000000000000
==================================================================
---
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