Subject: [syzbot] KASAN: use-after-free Read in nfc_llcp_sock_unlink

From: syzbot <[email-masked]>
Date: Mon, 29 Mar 2021 08:43:24 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    75887e88 Merge branch '40GbE' of git://git.kernel.org/pub/..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=12d6bb06d00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5adab0bdee099d7a
dashboard link: https://syzkaller.appspot.com/bug?extid=8b7c5fc0cfb74afee8d1
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15c2db21d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1091d4bed00000

The issue was bisected to:

commit 997acaf6b4b59c6a9c259740312a69ea549cc684
Author: Mark Rutland <[email-masked]>
Date:   Mon Jan 11 15:37:07 2021 +0000

    lockdep: report broken irq restoration

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12636d06d00000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=11636d06d00000
console output: https://syzkaller.appspot.com/x/log.txt?x=16636d06d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]
Fixes: 997acaf6b4b5 ("lockdep: report broken irq restoration")

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3e6f/0x54c0 kernel/locking/lockdep.c:4770
Read of size 8 at addr ffff888144614468 by task syz-executor242/8422

CPU: 0 PID: 8422 Comm: syz-executor242 Not tainted 5.12.0-rc4-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+0x141/0x1d7 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
 __kasan_report mm/kasan/report.c:399 [inline]
 kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
 __lock_acquire+0x3e6f/0x54c0 kernel/locking/lockdep.c:4770
 lock_acquire kernel/locking/lockdep.c:5510 [inline]
 lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475
 __raw_write_lock include/linux/rwlock_api_smp.h:210 [inline]
 _raw_write_lock+0x2a/0x40 kernel/locking/spinlock.c:295
 nfc_llcp_sock_unlink+0x1d/0x1c0 net/nfc/llcp_core.c:32
 llcp_sock_release+0x286/0x580 net/nfc/llcp_sock.c:640
 __sock_release+0xcd/0x280 net/socket.c:599
 sock_close+0x18/0x20 net/socket.c:1258
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:140
 exit_task_work include/linux/task_work.h:30 [inline]
 do_exit+0xbfc/0x2a60 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 __do_sys_exit_group kernel/exit.c:933 [inline]
 __se_sys_exit_group kernel/exit.c:931 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43db99
Code: Unable to access opcode bytes at RIP 0x43db6f.
RSP: 002b:00007ffdd4d753e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00000000004ae230 RCX: 000000000043db99
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000400488
R10: 0000000000400488 R11: 0000000000000246 R12: 00000000004ae230
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001

Allocated by task 1:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:427 [inline]
 ____kasan_kmalloc mm/kasan/common.c:506 [inline]
 ____kasan_kmalloc mm/kasan/common.c:465 [inline]
 __kasan_kmalloc+0x99/0xc0 mm/kasan/common.c:515
 kmalloc include/linux/slab.h:554 [inline]
 kzalloc include/linux/slab.h:684 [inline]
 nfc_llcp_register_device+0x45/0x9d0 net/nfc/llcp_core.c:1572
 nfc_register_device+0x6d/0x360 net/nfc/core.c:1124
 nfcsim_device_new+0x345/0x5c1 drivers/nfc/nfcsim.c:408
 nfcsim_init+0x71/0x14d drivers/nfc/nfcsim.c:455
 do_one_initcall+0x103/0x650 init/main.c:1226
 do_initcall_level init/main.c:1299 [inline]
 do_initcalls init/main.c:1315 [inline]
 do_basic_setup init/main.c:1335 [inline]
 kernel_init_freeable+0x63e/0x6c2 init/main.c:1537
 kernel_init+0xd/0x1b8 init/main.c:1424
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Freed by task 8422:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
 ____kasan_slab_free mm/kasan/common.c:360 [inline]
 ____kasan_slab_free mm/kasan/common.c:325 [inline]
 __kasan_slab_free+0xf5/0x130 mm/kasan/common.c:367
 kasan_slab_free include/linux/kasan.h:199 [inline]
 slab_free_hook mm/slub.c:1562 [inline]
 slab_free_freelist_hook+0x92/0x210 mm/slub.c:1600
 slab_free mm/slub.c:3161 [inline]
 kfree+0xe5/0x7f0 mm/slub.c:4213
 local_release net/nfc/llcp_core.c:175 [inline]
 kref_put include/linux/kref.h:65 [inline]
 nfc_llcp_local_put net/nfc/llcp_core.c:183 [inline]
 nfc_llcp_local_put+0x194/0x200 net/nfc/llcp_core.c:178
 llcp_sock_destruct+0x81/0x150 net/nfc/llcp_sock.c:950
 __sk_destruct+0x4b/0x900 net/core/sock.c:1795
 sk_destruct+0xbd/0xe0 net/core/sock.c:1839
 __sk_free+0xef/0x3d0 net/core/sock.c:1850
 sk_free+0x78/0xa0 net/core/sock.c:1861
 sock_put include/net/sock.h:1803 [inline]
 llcp_sock_release+0x3c9/0x580 net/nfc/llcp_sock.c:644
 __sock_release+0xcd/0x280 net/socket.c:599
 sock_close+0x18/0x20 net/socket.c:1258
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:140
 exit_task_work include/linux/task_work.h:30 [inline]
 do_exit+0xbfc/0x2a60 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 __do_sys_exit_group kernel/exit.c:933 [inline]
 __se_sys_exit_group kernel/exit.c:931 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff888144614000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1128 bytes inside of
 2048-byte region [ffff888144614000, ffff888144614800)
The buggy address belongs to the page:
page:ffffea0005118400 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888144616000 pfn:0x144610
head:ffffea0005118400 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head)
raw: 057ff00000010200 ffffea00050f2008 ffffea00050f1e08 ffff888010842000
raw: ffff888144616000 0000000000080006 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888144614300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888144614380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888144614400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff888144614480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888144614500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
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