[syzbot] KASAN: use-after-free Read in io_rsrc_node_ref_zero

syzbot
2022-02-21T22:17:25Z

Hello,

syzbot found the following issue on:

HEAD commit: 7f25f0412c9e Merge tag 'fs.mount_setattr.v5.17-rc4' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12255046700000
kernel config: https://syzkaller.appspot.com/x/.config?x=f6a069ed94a1ed1d
dashboard link: https://syzkaller.appspot.com/bug?extid=ca8bf833622a1662745b
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11bfa1de700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11d86902700000

The issue was bisected to:

commit b36a2050040b2d839bdc044007cdd57101d7f881
Author: Dylan Yudaken <dylany@fb.com>
Date: Fri Jan 21 12:38:56 2022 +0000

io_uring: fix bug in slow unregistering of nodes

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=150cfdee700000
final oops: https://syzkaller.appspot.com/x/report.txt?x=170cfdee700000
console output: https://syzkaller.appspot.com/x/log.txt?x=130cfdee700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ca8bf833622a1662745b@syzkaller.appspotmail.com
Fixes: b36a2050040b ("io_uring: fix bug in slow unregistering of nodes")

==================================================================
BUG: KASAN: use-after-free in io_rsrc_node_ref_zero+0x5a/0x274 fs/io_uring.c:7821
Read of size 8 at addr ffff888014fd2a00 by task syz-executor309/3618

CPU: 1 PID: 3618 Comm: syz-executor309 Not tainted 5.17.0-rc4-syzkaller-00241-g7f25f0412c9e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x8d/0x303 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
io_rsrc_node_ref_zero+0x5a/0x274 fs/io_uring.c:7821
percpu_ref_put_many.constprop.0+0x22b/0x260 include/linux/percpu-refcount.h:335
rcu_do_batch kernel/rcu/tree.c:2527 [inline]
rcu_core+0x7b1/0x1820 kernel/rcu/tree.c:2778
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
invoke_softirq kernel/softirq.c:432 [inline]
__irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:166 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:200
Code: 48 89 ef 5d e9 41 8b 46 00 5d be 03 00 00 00 e9 d6 f7 67 02 66 0f 1f 44 00 00 48 8b be b0 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 <65> 8b 05 39 5b 8a 7e 89 c1 48 8b 34 24 81 e1 00 01 00 00 65 48 8b
RSP: 0018:ffffc90002087e08 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000200 RCX: 0000000000000000
RDX: ffff88807e2b6140 RSI: ffffffff8167f8f4 RDI: 0000000000000003
RBP: 00000000000021ac R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff8167f8ea R11: 0000000000000001 R12: 0000000000000000
R13: dffffc0000000000 R14: 00007fa4f85b44ac R15: 00007ffe9f5e7080
__seqprop_raw_spinlock_sequence include/linux/seqlock.h:276 [inline]
timekeeping_get_delta kernel/time/timekeeping.c:252 [inline]
timekeeping_get_ns kernel/time/timekeeping.c:386 [inline]
ktime_get+0x19a/0x470 kernel/time/timekeeping.c:829
futex_init_timeout kernel/futex/syscalls.c:158 [inline]
__do_sys_futex kernel/futex/syscalls.c:177 [inline]
__se_sys_futex kernel/futex/syscalls.c:164 [inline]
__x64_sys_futex+0x388/0x4a0 kernel/futex/syscalls.c:164
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fa4f852b1c9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe9f5e04e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 000000000000babd RCX: 00007fa4f852b1c9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fa4f85b44ac
RBP: 0000000000000032 R08: 00007ffe9f5e7080 R09: 0000000000000000
R10: 00007ffe9f5e0520 R11: 0000000000000246 R12: 00007fa4f85b44ac
R13: 00007ffe9f5e0520 R14: 00007ffe9f5e0540 R15: 00007fa4f84e72d0
</TASK>

Allocated by task 3606:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa6/0xd0 mm/kasan/common.c:524
kasan_kmalloc include/linux/kasan.h:270 [inline]
__do_kmalloc mm/slab.c:3694 [inline]
__kmalloc+0x209/0x4d0 mm/slab.c:3703
io_rsrc_data_alloc+0x40/0x3b8 fs/io_uring.c:7968
io_sqe_buffers_register.cold+0x1f/0x443 fs/io_uring.c:9255
__io_uring_register fs/io_uring.c:11039 [inline]
__do_sys_io_uring_register+0x109b/0x15a0 fs/io_uring.c:11170
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 3606:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0xff/0x140 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:236 [inline]
__cache_free mm/slab.c:3437 [inline]
kfree+0xf8/0x2b0 mm/slab.c:3794
__io_sqe_buffers_unregister+0xf6/0x18d fs/io_uring.c:8997
io_sqe_buffers_unregister fs/io_uring.c:9012 [inline]
__io_uring_register fs/io_uring.c:11045 [inline]
__do_sys_io_uring_register.cold+0x28f/0x1611 fs/io_uring.c:11170
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff888014fd2a00
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 0 bytes inside of
192-byte region [ffff888014fd2a00, ffff888014fd2ac0)
The buggy address belongs to the page:
page:ffffea000053f480 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14fd2
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea000053f388 ffffea000052fac8 ffff888010c40000
raw: 0000000000000000 ffff888014fd2000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 1, ts 2173654799, free_ts 0
prep_new_page mm/page_alloc.c:2434 [inline]
get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
__alloc_pages_node include/linux/gfp.h:572 [inline]
kmem_getpages mm/slab.c:1378 [inline]
cache_grow_begin+0x75/0x390 mm/slab.c:2584
cache_alloc_refill+0x27f/0x380 mm/slab.c:2957
____cache_alloc mm/slab.c:3040 [inline]
____cache_alloc mm/slab.c:3023 [inline]
__do_cache_alloc mm/slab.c:3267 [inline]
slab_alloc mm/slab.c:3308 [inline]
kmem_cache_alloc_trace+0x380/0x4a0 mm/slab.c:3565
kmalloc include/linux/slab.h:581 [inline]
kzalloc include/linux/slab.h:715 [inline]
call_usermodehelper_setup+0x9d/0x340 kernel/umh.c:365
kobject_uevent_env+0xf28/0x1600 lib/kobject_uevent.c:614
kernel_add_sysfs_param kernel/params.c:816 [inline]
param_sysfs_builtin kernel/params.c:851 [inline]
param_sysfs_init+0x367/0x43b kernel/params.c:970
do_one_initcall+0x103/0x650 init/main.c:1300
do_initcall_level init/main.c:1373 [inline]
do_initcalls init/main.c:1389 [inline]
do_basic_setup init/main.c:1408 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1613
kernel_init+0x1a/0x1d0 init/main.c:1502
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page_owner free stack trace missing

Memory state around the buggy address:
ffff888014fd2900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888014fd2980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888014fd2a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888014fd2a80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff888014fd2b00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 48 89 ef mov %rbp,%rdi
3: 5d pop %rbp
4: e9 41 8b 46 00 jmpq 0x468b4a
9: 5d pop %rbp
a: be 03 00 00 00 mov $0x3,%esi
f: e9 d6 f7 67 02 jmpq 0x267f7ea
14: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
1a: 48 8b be b0 01 00 00 mov 0x1b0(%rsi),%rdi
21: e8 b4 ff ff ff callq 0xffffffda
26: 31 c0 xor %eax,%eax
28: c3 retq
29: 90 nop
* 2a: 65 8b 05 39 5b 8a 7e mov %gs:0x7e8a5b39(%rip),%eax # 0x7e8a5b6a <-- trapping instruction
31: 89 c1 mov %eax,%ecx
33: 48 8b 34 24 mov (%rsp),%rsi
37: 81 e1 00 01 00 00 and $0x100,%ecx
3d: 65 gs
3e: 48 rex.W
3f: 8b .byte 0x8b

---
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