KASAN: use-after-free Read in lock_sock

KASAN: use-after-free Read in lock_sock_nested
Status: upstream: reported syz repro on 2019/01/02 10:41
Reported-by: syzbot+500c69d1e21d970e461b@syzkaller.appspotmail.com
First crash: 197d, last: 46d

Bisection: the bug happens on the oldest tested release (bisect log)
Tree: linux-next
Crash: inconsistent lock state in nr_find_socket (log)
Repro: syz .config

similar bugs (3):
Kernel	Title	Repro	Count	Last	Reported	Patched	Status
linux-4.14	KASAN: use-after-free Read in lock_sock_nested	syz	11	6d14h	85d	0/1	upstream: reported syz repro on 2019/04/24 06:28
android-44	KASAN: use-after-free Read in lock_sock_nested	C	40	327d	98d	0/2	public: reported C repro on 2019/04/11 08:44
android-49	KASAN: use-after-free Read in lock_sock_nested	C	39	329d	522d	0/3	closed as invalid on 2019/03/07 05:41

Sample crash report:

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3150/0x4710 kernel/locking/lockdep.c:3200
Read of size 8 at addr ffff8880195faa60 by task syz-executor.4/7495

CPU: 1 PID: 7495 Comm: syz-executor.4 Not tainted 5.0.0-rc6-next-20190214 #35
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 __lock_acquire+0x3150/0x4710 kernel/locking/lockdep.c:3200
 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3833
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:168
 spin_lock_bh include/linux/spinlock.h:334 [inline]
 lock_sock_nested+0x41/0x120 net/core/sock.c:2878
 lock_sock include/net/sock.h:1507 [inline]
 nr_accept+0x200/0x790 net/netrom/af_netrom.c:808
 __sys_accept4+0x350/0x6a0 net/socket.c:1610
 __do_sys_accept net/socket.c:1651 [inline]
 __se_sys_accept net/socket.c:1648 [inline]
 __x64_sys_accept+0x75/0xb0 net/socket.c:1648
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457e29
Code: ad b8 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f16cb51ec78 EFLAGS: 00000246 ORIG_RAX: 000000000000002b
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457e29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f16cb51f6d4
R13: 00000000004bdbf0 R14: 00000000004cde80 R15: 00000000ffffffff

Allocated by task 7492:
 save_stack+0x45/0xd0 mm/kasan/common.c:75
 set_track mm/kasan/common.c:87 [inline]
 __kasan_kmalloc mm/kasan/common.c:497 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:470
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:511
 __do_kmalloc mm/slab.c:3721 [inline]
 __kmalloc+0x15c/0x740 mm/slab.c:3730
 kmalloc include/linux/slab.h:553 [inline]
 sk_prot_alloc+0x19c/0x2e0 net/core/sock.c:1573
 sk_alloc+0x39/0xf70 net/core/sock.c:1627
 nr_create+0xb9/0x5e0 net/netrom/af_netrom.c:436
 __sock_create+0x3e6/0x750 net/socket.c:1297
 sock_create net/socket.c:1337 [inline]
 __sys_socket+0x103/0x220 net/socket.c:1367
 __do_sys_socket net/socket.c:1376 [inline]
 __se_sys_socket net/socket.c:1374 [inline]
 __x64_sys_socket+0x73/0xb0 net/socket.c:1374
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7491:
 save_stack+0x45/0xd0 mm/kasan/common.c:75
 set_track mm/kasan/common.c:87 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:459
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:467
 __cache_free mm/slab.c:3491 [inline]
 kfree+0xcf/0x230 mm/slab.c:3816
 sk_prot_free net/core/sock.c:1610 [inline]
 __sk_destruct+0x4f1/0x6d0 net/core/sock.c:1692
 sk_destruct+0x7b/0x90 net/core/sock.c:1700
 __sk_free+0xce/0x300 net/core/sock.c:1711
 sk_free+0x42/0x50 net/core/sock.c:1722
 sock_put include/net/sock.h:1708 [inline]
 nr_release+0x337/0x3c0 net/netrom/af_netrom.c:557
 __sock_release+0xd3/0x250 net/socket.c:579
 sock_close+0x1b/0x30 net/socket.c:1161
 __fput+0x2e5/0x8d0 fs/file_table.c:278
 ____fput+0x16/0x20 fs/file_table.c:309
 task_work_run+0x14a/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880195fa9c0
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 160 bytes inside of
 2048-byte region [ffff8880195fa9c0, ffff8880195fb1c0)
The buggy address belongs to the page:
page:ffffea0000657e80 count:1 mapcount:0 mapping:ffff88812c3f0c40 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00026f8a88 ffffea000220c888 ffff88812c3f0c40
raw: 0000000000000000 ffff8880195fa140 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880195fa900: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880195fa980: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880195faa00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff8880195faa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880195fab00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

All crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	Maintainers
ci-upstream-linux-next-kasan-gce-root	2019/02/15 05:24	linux-next	b3418f8b	76dd003f	.config	log	report	syz	davem@davemloft.net, linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ralf@linux-mips.org
ci-upstream-kasan-gce-selinux-root	2019/01/01 20:21	upstream	e1ef035d	3d85f48c	.config	log	report		davem@davemloft.net, linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ralf@linux-mips.org
ci-upstream-kasan-gce-smack-root	2019/04/24 05:04	upstream	7142eaa5	4d3d6a50	.config	log	report		davem@davemloft.net, linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ralf@linux-mips.org
ci-upstream-kasan-gce-selinux-root	2019/02/15 08:35	upstream	cb5b020a	76dd003f	.config	log	report		davem@davemloft.net, linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ralf@linux-mips.org
ci-upstream-net-this-kasan-gce	2019/06/02 06:42	net	e8d67fa5	53c81ea5	.config	log	report		davem@davemloft.net, linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ralf@linux-mips.org
ci-upstream-net-kasan-gce	2019/03/16 10:18	net-next	3b319ee2	bab43553	.config	log	report		davem@davemloft.net, linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ralf@linux-mips.org