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KASAN: use-after-free Read in fuse_kill_sb_blk

Status: fixed on 2018/07/09 18:05
Subsystems: fuse
[Documentation on labels]
Reported-by: syzbot+ec3986119086fe4eec97@syzkaller.appspotmail.com
Fix commit: 543b8f8662fe fuse: don't keep dead fuse_conn at fuse_fill_super().
First crash: 2766d, last: 2747d
▶ ▼ Duplicate bugs (2)
duplicates (2):
Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
KASAN: use-after-free Read in should_fail mm 19 C 2 2761d 2762d 0/29 closed as dup on 2018/05/04 13:17
KASAN: use-after-free Read in fuse_kill_sb_anon fuse 19 16 2728d 2762d 0/29 closed as dup on 2018/05/04 17:19
▶ ▼ Discussions (8)
Title Replies (including bot) Last reply
[PATCH 3.16 000/366] 3.16.61-rc1 review 375 (376) 2019/01/02 17:44
[PATCH 4.9 000/101] 4.9.111-stable review 110 (110) 2018/10/09 06:56
[PATCH 4.4 000/105] 4.4.139-stable review 106 (106) 2018/07/26 15:09
[PATCH 3.18 00/85] 3.18.114-stable review 84 (84) 2018/07/03 09:17
[PATCH 4.17 000/220] 4.17.4-stable review 219 (219) 2018/07/03 06:31
[PATCH 4.14 000/157] 4.14.53-stable review 156 (156) 2018/07/02 16:32
[PATCH] fuse: don't keep dead fuse_conn at fuse_fill_super(). 3 (3) 2018/05/31 10:19
KASAN: use-after-free Read in fuse_kill_sb_blk 1 (2) 2018/05/01 10:03

Sample crash report:
RDX: 00000000004ba385 RSI: 0000000020000100 RDI: 0000000020000140
RBP: 0000000020000140 R08: 00007f287979db20 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3888/0x5140 kernel/locking/lockdep.c:3310
Read of size 8 at addr ffff8801afe4d988 by task syz-executor4/5884

CPU: 0 PID: 5884 Comm: syz-executor4 Not tainted 4.17.0-rc5+ #59
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+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 __lock_acquire+0x3888/0x5140 kernel/locking/lockdep.c:3310
 lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920
 down_write+0x87/0x120 kernel/locking/rwsem.c:70
 fuse_kill_sb_blk+0x50/0xb0 fs/fuse/inode.c:1230
 deactivate_locked_super+0x97/0x100 fs/super.c:316
 mount_bdev+0x37d/0x3e0 fs/super.c:1166
 fuse_mount_blk+0x34/0x40 fs/fuse/inode.c:1222
 mount_fs+0xae/0x328 fs/super.c:1267
 vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:1027 [inline]
 do_new_mount fs/namespace.c:2518 [inline]
 do_mount+0x564/0x3070 fs/namespace.c:2848
 ksys_mount+0x12d/0x140 fs/namespace.c:3064
 __do_sys_mount fs/namespace.c:3078 [inline]
 __se_sys_mount fs/namespace.c:3075 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455a09
RSP: 002b:00007f287979db08 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000016 RCX: 0000000000455a09
RDX: 00000000004ba385 RSI: 0000000020000100 RDI: 0000000020000140
RBP: 0000000020000140 R08: 00007f287979db20 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 5884:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
 kmalloc include/linux/slab.h:512 [inline]
 fuse_fill_super+0xc92/0x1e20 fs/fuse/inode.c:1096
 mount_bdev+0x30c/0x3e0 fs/super.c:1164
 fuse_mount_blk+0x34/0x40 fs/fuse/inode.c:1222
 mount_fs+0xae/0x328 fs/super.c:1267
 vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:1027 [inline]
 do_new_mount fs/namespace.c:2518 [inline]
 do_mount+0x564/0x3070 fs/namespace.c:2848
 ksys_mount+0x12d/0x140 fs/namespace.c:3064
 __do_sys_mount fs/namespace.c:3078 [inline]
 __se_sys_mount fs/namespace.c:3075 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10843:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 __rcu_reclaim kernel/rcu/rcu.h:173 [inline]
 rcu_do_batch kernel/rcu/tree.c:2675 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2930 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2897 [inline]
 rcu_process_callbacks+0xa69/0x15f0 kernel/rcu/tree.c:2914
 __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801afe4d6c0
 which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 712 bytes inside of
 1024-byte region [ffff8801afe4d6c0, ffff8801afe4dac0)
The buggy address belongs to the page:
page:ffffea0006bf9300 count:1 mapcount:0 mapping:ffff8801afe4c040 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801afe4c040 0000000000000000 0000000100000007
raw: ffffea0007652ea0 ffffea00061c7ea0 ffff8801da800ac0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801afe4d880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801afe4d900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801afe4d980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff8801afe4da00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801afe4da80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/05/19 23:54 upstream 0b449a441dac f48c20b8 .config console log report ci-upstream-kasan-gce-root
2018/05/15 14:05 upstream 67b8d5c70812 661fd7b9 .config console log report ci-upstream-kasan-gce-root
2018/05/12 15:58 upstream f0ab773f5c96 e726f42b .config console log report ci-upstream-kasan-gce-root
2018/04/30 11:55 upstream 6da6c0db5316 06db3cec .config console log report ci-upstream-kasan-gce-root
* Struck through repros no longer work on HEAD.