KASAN: use-after-free Read in kernfs_put

From: syzbot
Date: Wed Dec 19 2018 - 13:44:06 EST

Next message: Manfred Schlaegl: "[PATCH] Revert "can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb""
Previous message: Dmitry Vyukov: "Re: INFO: rcu detected stall in sys_sendfile64"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hello,

syzbot found the following crash on:

HEAD commit: 1a9430db2835 ima: cleanup the match_token policy code
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16518f6d400000
kernel config: https://syzkaller.appspot.com/x/.config?x=861a3573f4e78ba1
dashboard link: https://syzkaller.appspot.com/bug?extid=beac00daeba8d7a7d757
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+beac00daeba8d7a7d757@xxxxxxxxxxxxxxxxxxxxxxxxx

RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5b7d6886d4
R13: 00000000004c5d63 R14: 00000000004da6c8 R15: 0000000000000004
Bluetooth: Can't register HCI device
==================================================================
BUG: KASAN: use-after-free in kernfs_put+0x6d2/0x760 fs/kernfs/dir.c:535
Read of size 8 at addr ffff8881c4a58c50 by task syz-executor3/11154

CPU: 0 PID: 11154 Comm: syz-executor3 Not tainted 4.20.0-rc7+ #155
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
kernfs_put+0x6d2/0x760 fs/kernfs/dir.c:535
kernfs_create_dir_ns+0x12e/0x160 fs/kernfs/dir.c:1035
sysfs_create_dir_ns+0x19b/0x340 fs/sysfs/dir.c:58
create_dir lib/kobject.c:88 [inline]
kobject_add_internal.cold.11+0x116/0x6af lib/kobject.c:247
kobject_add_varg lib/kobject.c:382 [inline]
kobject_add+0x13f/0x1b0 lib/kobject.c:426
device_add+0x445/0x18e0 drivers/base/core.c:1879
hci_register_dev+0x3b3/0x9c0 net/bluetooth/hci_core.c:3261
__vhci_create_device+0x2c1/0x580 drivers/bluetooth/hci_vhci.c:139
vhci_create_device drivers/bluetooth/hci_vhci.c:163 [inline]
vhci_get_user drivers/bluetooth/hci_vhci.c:219 [inline]
vhci_write+0x2de/0x470 drivers/bluetooth/hci_vhci.c:299
call_write_iter include/linux/fs.h:1857 [inline]
new_sync_write fs/read_write.c:474 [inline]
__vfs_write+0x6b8/0x9f0 fs/read_write.c:487
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
vfs_write+0x1fc/0x560 fs/read_write.c:549
ksys_write+0x101/0x260 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457669
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f0d9d4dac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457669
RDX: 0000000000000002 RSI: 00000000200000c0 RDI: 0000000000000005
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0d9d4db6d4
R13: 00000000004c5d63 R14: 00000000004da6c8 R15: 00000000ffffffff

Allocated by task 7609:
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_trace+0x152/0x750 mm/slab.c:3620
kmalloc include/linux/slab.h:546 [inline]
kzalloc include/linux/slab.h:741 [inline]
kernfs_iattrs.isra.4+0x116/0x400 fs/kernfs/inode.c:45
kernfs_xattr_get+0x67/0xb0 fs/kernfs/inode.c:316
__vfs_getxattr+0xee/0x150 fs/xattr.c:310
smk_fetch.part.24+0x7e/0x100 security/smack/smack_lsm.c:277
smk_fetch security/smack/smack_lsm.c:3555 [inline]
smack_d_instantiate+0x94e/0xea0 security/smack/smack_lsm.c:3509
security_d_instantiate+0x5c/0xf0 security/security.c:1298
d_splice_alias+0x120/0x11d0 fs/dcache.c:2911
CPU: 1 PID: 11171 Comm: syz-executor2 Not tainted 4.20.0-rc7+ #155
kernfs_iop_lookup+0x1bf/0x230 fs/kernfs/dir.c:1103
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
__lookup_slow+0x2b5/0x540 fs/namei.c:1671
Call Trace:
lookup_slow+0x57/0x80 fs/namei.c:1688
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x244/0x39d lib/dump_stack.c:113
walk_component+0x92b/0x2590 fs/namei.c:1810
link_path_walk.part.40+0xa61/0x1530 fs/namei.c:2141
link_path_walk fs/namei.c:2269 [inline]
path_lookupat.isra.43+0xf7/0xc00 fs/namei.c:2317
filename_lookup+0x26a/0x520 fs/namei.c:2348
fail_dump lib/fault-inject.c:51 [inline]
should_fail.cold.4+0xa/0x17 lib/fault-inject.c:149
user_path_at_empty+0x40/0x50 fs/namei.c:2608
do_readlinkat+0x156/0x410 fs/stat.c:397
__do_sys_readlink fs/stat.c:430 [inline]
__se_sys_readlink fs/stat.c:427 [inline]
__x64_sys_readlink+0x78/0xb0 fs/stat.c:427
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7609:
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
__should_failslab+0x124/0x180 mm/failslab.c:32
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
should_failslab+0x9/0x14 mm/slab_common.c:1578
__cache_free mm/slab.c:3498 [inline]
kfree+0xcf/0x230 mm/slab.c:3817
slab_pre_alloc_hook mm/slab.h:423 [inline]
slab_alloc mm/slab.c:3378 [inline]
__do_kmalloc mm/slab.c:3720 [inline]
__kmalloc+0x2e0/0x760 mm/slab.c:3731
kernfs_put+0x3b9/0x760 fs/kernfs/dir.c:540
kernfs_evict_inode+0x50/0x60 fs/kernfs/inode.c:289
evict+0x4b9/0x980 fs/inode.c:558
kmalloc include/linux/slab.h:551 [inline]
kzalloc include/linux/slab.h:741 [inline]
__alloc_workqueue_key+0x1dc/0x10a0 kernel/workqueue.c:4076
iput_final fs/inode.c:1550 [inline]
iput+0x679/0xa90 fs/inode.c:1576
dentry_unlink_inode+0x461/0x5e0 fs/dcache.c:360
__dentry_kill+0x44c/0x7a0 fs/dcache.c:552
dentry_kill+0xc9/0x680 fs/dcache.c:671
dput.part.25+0x660/0x860 fs/dcache.c:832
dput+0x15/0x20 fs/dcache.c:814
lookup_fast+0xd68/0x12a0 fs/namei.c:1625
walk_component+0x139/0x2590 fs/namei.c:1806
link_path_walk.part.40+0xa61/0x1530 fs/namei.c:2141
link_path_walk fs/namei.c:2072 [inline]
path_openat+0x270/0x5150 fs/namei.c:3533
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x568/0x700 fs/open.c:1063
hci_register_dev+0x2ad/0x9c0 net/bluetooth/hci_core.c:3248
__do_sys_open fs/open.c:1081 [inline]
__se_sys_open fs/open.c:1076 [inline]
__x64_sys_open+0x7e/0xc0 fs/open.c:1076
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

__vhci_create_device+0x2c1/0x580 drivers/bluetooth/hci_vhci.c:139
The buggy address belongs to the object at ffff8881c4a58c00
which belongs to the cache kmalloc-192 of size 192
vhci_create_device drivers/bluetooth/hci_vhci.c:163 [inline]
vhci_get_user drivers/bluetooth/hci_vhci.c:219 [inline]
vhci_write+0x2de/0x470 drivers/bluetooth/hci_vhci.c:299
The buggy address is located 80 bytes inside of
192-byte region [ffff8881c4a58c00, ffff8881c4a58cc0)
call_write_iter include/linux/fs.h:1857 [inline]
new_sync_write fs/read_write.c:474 [inline]
__vfs_write+0x6b8/0x9f0 fs/read_write.c:487
The buggy address belongs to the page:
page:ffffea0007129600 count:1 mapcount:0 mapping:ffff8881da800040 index:0xffff8881c4a58500
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffffea0007340b48 ffffea000765b148 ffff8881da800040
vfs_write+0x1fc/0x560 fs/read_write.c:549
raw: ffff8881c4a58500 ffff8881c4a58000 000000010000000b 0000000000000000
ksys_write+0x101/0x260 fs/read_write.c:598
page dumped because: kasan: bad access detected

Memory state around the buggy address:
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
ffff8881c4a58b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
ffff8881c4a58b80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc

ffff8881c4a58c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff8881c4a58c80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8881c4a58d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457669
kobject: 'loop1' (000000000073d129): kobject_uevent_env
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
kobject: 'loop1' (000000000073d129): fill_kobj_path: path = '/devices/virtual/block/loop1'
RSP: 002b:00007f5b7d687c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f5b7d687c90 RCX: 0000000000457669
RDX: 0000000000000002 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5b7d6886d4
R13: 00000000004c5d63 R14: 00000000004da6c8 R15: 0000000000000004
kobject: 'rfkill147' (00000000e92224a0): kobject_add_internal: parent: 'hci0', set: 'devices'

---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot.

Next message: Manfred Schlaegl: "[PATCH] Revert "can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb""
Previous message: Dmitry Vyukov: "Re: INFO: rcu detected stall in sys_sendfile64"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]