KASAN: use-after-free Read in inet_shutdown

Status: fixed on 2018/03/06 13:29
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+347bd5acde002e353a36@syzkaller.appspotmail.com
Fix commit: 28f5bfb81919 l2tp: fix tunnel lookup use-after-free race
First crash: 3128d, last: 3081d
▶ ▼ Discussions (7)
Title Replies (including bot) Last reply
[PATCH 3.16 000/410] 3.16.57-rc1 review 426 (426) 2018/11/12 17:42
[PATCH 4.15 000/122] 4.15.8-stable review 135 (135) 2018/03/08 17:51
[PATCH net 0/5] l2tp: fix API races discovered by syzbot 7 (7) 2018/02/26 17:21
[PATCH net-next v2 00/16] l2tp: fix API races discovered by syzbot 27 (27) 2018/02/15 08:23
[PATCH net-next v3 00/16] l2tp: fix API races discovered by syzbot 18 (18) 2018/02/12 19:00
[PATCH net-next 00/16] l2tp: fix API races discovered by syzbot 18 (18) 2018/02/12 03:37
KASAN: use-after-free Read in inet_shutdown 0 (2) 2018/02/02 17:47
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 KASAN: use-after-free Read in inet_shutdown (2) 19 4 1667d 1748d 0/1 auto-closed as invalid on 2022/05/17 02:29
android-44 KASAN: use-after-free Read in inet_shutdown 19 syz 8 2912d 2676d 0/2 public: reported syz repro on 2019/04/14 00:02
linux-4.14 KASAN: use-after-free Read in inet_shutdown 19 12 1911d 2005d 0/1 auto-closed as invalid on 2021/09/14 22:13
android-49 KASAN: use-after-free Read in inet_shutdown 19 syz, C 51 2908d 2677d 0/3 public: reported C repro on 2019/04/13 00:00

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in inet_shutdown+0x2d4/0x350 net/ipv4/af_inet.c:819
Read of size 4 at addr ffff8801c008f540 by task syzkaller114342/5197

CPU: 0 PID: 5197 Comm: syzkaller114342 Not tainted 4.15.0+ #292
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 inet_shutdown+0x2d4/0x350 net/ipv4/af_inet.c:819
 pppol2tp_session_close+0x92/0xf0 net/l2tp/l2tp_ppp.c:430
 l2tp_tunnel_closeall+0x305/0x410 net/l2tp/l2tp_core.c:1285
 l2tp_udp_encap_destroy+0x95/0x100 net/l2tp/l2tp_core.c:1308
 udpv6_destroy_sock+0x161/0x190 net/ipv6/udp.c:1407
 sk_common_release+0x6b/0x2f0 net/core/sock.c:2999
 udp_lib_close+0x15/0x20 include/net/udp.h:203
 inet_release+0xed/0x1c0 net/ipv4/af_inet.c:427
 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:435
 sock_release+0x8d/0x1e0 net/socket.c:595
 sock_close+0x16/0x20 net/socket.c:1149
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x9e/0xa0
RIP: 0033:0x44bbd9
RSP: 002b:00007f8e19861ce8 EFLAGS: 00000206 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00000000006ddc24 RCX: 000000000044bbd9
RDX: 000000000044bbd9 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000006ddc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007ffc84c0bb3f R14: 00007f8e198629c0 R15: 000000000000000d

Allocated by task 5216:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3540
 sock_alloc_inode+0x70/0x300 net/socket.c:244
 alloc_inode+0x65/0x180 fs/inode.c:209
 new_inode_pseudo+0x69/0x190 fs/inode.c:891
 sock_alloc+0x41/0x270 net/socket.c:565
 __sock_create+0x148/0x850 net/socket.c:1249
 sock_create net/socket.c:1325 [inline]
 SYSC_socket net/socket.c:1355 [inline]
 SyS_socket+0xeb/0x1d0 net/socket.c:1335
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 5291:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3484 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3742
 sock_destroy_inode+0x56/0x70 net/socket.c:274
 destroy_inode+0x15d/0x200 fs/inode.c:266
 evict+0x57e/0x920 fs/inode.c:571
 iput_final fs/inode.c:1516 [inline]
 iput+0x7b9/0xaf0 fs/inode.c:1543
 dentry_unlink_inode+0x4b0/0x5e0 fs/dcache.c:371
 __dentry_kill+0x3de/0x700 fs/dcache.c:575
 dentry_kill fs/dcache.c:616 [inline]
 dput.part.21+0x6fb/0x830 fs/dcache.c:826
 dput+0x1f/0x30 fs/dcache.c:790
 __fput+0x51c/0x7e0 fs/file_table.c:227
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x9e/0xa0

The buggy address belongs to the object at ffff8801c008f540
 which belongs to the cache sock_inode_cache of size 992
The buggy address is located 0 bytes inside of
 992-byte region [ffff8801c008f540, ffff8801c008f920)
The buggy address belongs to the page:
page:ffffea00070023c0 count:1 mapcount:0 mapping:ffff8801c008f0c0 index:0xffff8801c008fffd
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c008f0c0 ffff8801c008fffd 0000000100000003
raw: ffffea00070023a0 ffffea00070024a0 ffff8801d9fe6380 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c008f400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c008f480: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801c008f500: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                           ^
 ffff8801c008f580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c008f600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (22):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/02/02 17:46 upstream 4bf772b14675 632a8c2c .config console log report syz C ci-upstream-kasan-gce
2018/02/11 01:50 upstream d48fcbd864a0 4e9b726d .config console log report syz C ci-upstream-kasan-gce-386
2018/02/26 01:36 upstream c89be5242607 9fe8aa42 .config console log report ci-upstream-kasan-gce
2018/02/08 02:58 upstream 581e400ff935 9fb5ec43 .config console log report ci-upstream-kasan-gce
2018/02/07 10:49 upstream cbd7b8a76b79 66c15deb .config console log report ci-upstream-kasan-gce
2018/02/04 15:02 upstream 617aebe6a97e a1bc9d40 .config console log report ci-upstream-kasan-gce
2018/02/02 18:49 upstream 4bf772b14675 632a8c2c .config console log report ci-upstream-kasan-gce
2018/02/02 17:27 upstream 4bf772b14675 632a8c2c .config console log report ci-upstream-kasan-gce
2018/01/31 01:58 upstream 72906f38934a 02553e22 .config console log report ci-upstream-kasan-gce
2018/01/29 07:22 upstream 24b1cccf9229 08d47756 .config console log report ci-upstream-kasan-gce
2018/01/24 18:34 upstream 5132ede0fe80 a5b7566c .config console log report ci-upstream-kasan-gce
2018/01/24 03:35 upstream 1f07476ec143 a5b7566c .config console log report ci-upstream-kasan-gce
2018/01/23 07:17 upstream a0ec1ded22e6 228e3d95 .config console log report ci-upstream-kasan-gce
2018/01/22 03:47 upstream 5515114211c5 fbbdcd92 .config console log report ci-upstream-kasan-gce
2018/01/19 09:01 upstream dda3e15231b3 161c1d64 .config console log report ci-upstream-kasan-gce
2018/02/12 10:59 upstream 7928b2cbe55b 88bc17df .config console log report ci-upstream-kasan-gce-386
2018/01/21 04:48 net-next-old ea9722e2650d fbbdcd92 .config console log report ci-upstream-net-kasan-gce
2018/03/04 11:45 net-next-old e4e31cf07d0c 2c6f473e .config console log report ci-upstream-net-kasan-gce
2018/01/21 02:22 mmots 2734fabdcba4 fbbdcd92 .config console log report ci-upstream-mmots-kasan-gce
2018/01/19 13:27 mmots 216435561218 161c1d64 .config console log report ci-upstream-mmots-kasan-gce
2018/01/19 08:39 mmots 216435561218 161c1d64 .config console log report ci-upstream-mmots-kasan-gce
2018/01/16 17:43 mmots ce3c209f6733 4198e588 .config console log report ci-upstream-mmots-kasan-gce
* Struck through repros no longer work on HEAD.