syzbot


KASAN: use-after-free Read in refcount_inc_not_zero_checked

Status: fixed on 2019/03/06 07:43
Reported-by: syzbot+defa700d16f1bd1b9a05@syzkaller.appspotmail.com
Fix commit: 63346650c1a9 netrom: switch to sock timer API
First crash: 1490d, last: 1430d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in refcount_inc_not_zero_checked (2) syz inconclusive done 2 985d 1416d 0/24 upstream: reported syz repro on 2019/03/16 20:12
linux-4.19 KASAN: use-after-free Read in refcount_inc_not_zero_checked 1 1371d 1371d 0/1 auto-closed as invalid on 2019/10/25 08:52

Sample crash report:
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
IPVS: ftp: loaded support on port[0] = 21
chnl_net:caif_netlink_parms(): no params data found
==================================================================
BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x91/0x2e0 lib/refcount.c:120
Read of size 4 at addr ffff888089bba440 by task syz-executor5/11381

CPU: 1 PID: 11381 Comm: syz-executor5 Not tainted 5.0.0-rc3+ #40
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+0x1db/0x2d0 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
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 kasan_check_read+0x11/0x20 mm/kasan/common.c:100
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 refcount_inc_not_zero_checked+0x91/0x2e0 lib/refcount.c:120
 refcount_inc_checked+0x17/0x70 lib/refcount.c:153
 sock_hold include/net/sock.h:647 [inline]
 nr_release+0x62/0x3c0 net/netrom/af_netrom.c:523
 __sock_release+0xd3/0x250 net/socket.c:579
 sock_close+0x1b/0x30 net/socket.c:1141
 __fput+0x3c5/0xb10 fs/file_table.c:278
 ____fput+0x16/0x20 fs/file_table.c:309
 task_work_run+0x1f4/0x2b0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xad7/0x26e0 kernel/exit.c:867
 do_group_exit+0x177/0x430 kernel/exit.c:971
 get_signal+0x8b4/0x19b0 kernel/signal.c:2517
 do_signal+0x91/0x1ea0 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x2f7/0x3b0 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458099
Code: 6d b7 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7c8a6a7cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000073c228 RCX: 0000000000458099
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000073c228
RBP: 000000000073c220 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000073c22c
R13: 00007ffc1cd8e9ef R14: 00007f7c8a6a89c0 R15: 0000000000000005

Allocated by task 11350:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc mm/kasan/common.c:496 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:504
 __do_kmalloc mm/slab.c:3711 [inline]
 __kmalloc+0x15c/0x740 mm/slab.c:3720
 kmalloc include/linux/slab.h:550 [inline]
 sk_prot_alloc+0x19c/0x2e0 net/core/sock.c:1477
 sk_alloc+0xd7/0x1690 net/core/sock.c:1531
 nr_create+0xb9/0x5e0 net/netrom/af_netrom.c:436
 __sock_create+0x532/0x930 net/socket.c:1277
 sock_create net/socket.c:1317 [inline]
 __sys_socket+0x106/0x260 net/socket.c:1347
 __do_sys_socket net/socket.c:1356 [inline]
 __se_sys_socket net/socket.c:1354 [inline]
 __x64_sys_socket+0x73/0xb0 net/socket.c:1354
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 11170:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:458
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:466
 __cache_free mm/slab.c:3487 [inline]
 kfree+0xcf/0x230 mm/slab.c:3806
 sk_prot_free net/core/sock.c:1514 [inline]
 __sk_destruct+0x76d/0xa60 net/core/sock.c:1596
 sk_destruct+0x7b/0x90 net/core/sock.c:1604
 __sk_free+0xce/0x300 net/core/sock.c:1615
 sk_free+0x42/0x50 net/core/sock.c:1626
 sock_put include/net/sock.h:1707 [inline]
 nr_heartbeat_expiry+0x489/0x520 net/netrom/nr_timer.c:130
 call_timer_fn+0x254/0x900 kernel/time/timer.c:1325
 expire_timers kernel/time/timer.c:1362 [inline]
 __run_timers+0x6fc/0xd50 kernel/time/timer.c:1681
 run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1694
 __do_softirq+0x30b/0xb11 kernel/softirq.c:292

The buggy address belongs to the object at ffff888089bba3c0
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 128 bytes inside of
 2048-byte region [ffff888089bba3c0, ffff888089bbabc0)
The buggy address belongs to the page:
page:ffffea000226ee80 count:1 mapcount:0 mapping:ffff88812c3f0c40 index:0xffff888089bbb4c0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0002608f08 ffffea0002501688 ffff88812c3f0c40
raw: ffff888089bbb4c0 ffff888089bba3c0 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888089bba300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888089bba380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff888089bba400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888089bba480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888089bba500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (24):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci-upstream-kasan-gce-smack-root 2019/01/23 20:44 upstream 333478a7eb21 7cf3249c .config console log report syz
ci-upstream-net-this-kasan-gce 2019/02/15 05:03 net 8d6ea932856c 76dd003f .config console log report syz
ci-upstream-net-kasan-gce 2019/02/15 05:26 net-next f8b1f9f6459c 76dd003f .config console log report syz
ci-upstream-kasan-gce-root 2019/03/02 21:27 upstream c93d9218ea56 1c0e457a .config console log report
ci-upstream-kasan-gce-selinux-root 2019/02/26 23:36 upstream 7d762d69145a f2468c12 .config console log report
ci-upstream-kasan-gce-selinux-root 2019/02/25 09:01 upstream 5908e6b738e3 a70141bf .config console log report
ci-upstream-kasan-gce-smack-root 2019/01/23 14:44 upstream 333478a7eb21 7cf3249c .config console log report
ci-upstream-kasan-gce-selinux-root 2019/01/23 14:37 upstream 333478a7eb21 7cf3249c .config console log report
ci-upstream-kasan-gce-root 2019/01/11 16:36 upstream 1bdbe2274920 c3f3344c .config console log report
ci-upstream-kasan-gce-root 2019/01/05 19:03 upstream 3fed6ae4b027 53be0a37 .config console log report
ci-upstream-kasan-gce-smack-root 2019/01/04 13:20 upstream 96d4f267e40f 7da23925 .config console log report
ci-upstream-kasan-gce-smack-root 2019/01/04 00:09 upstream 645ff1e8e704 7da23925 .config console log report
ci-upstream-kasan-gce-root 2019/01/03 19:23 upstream 645ff1e8e704 66fcd29b .config console log report
ci-upstream-net-this-kasan-gce 2019/02/06 13:29 net bdcc5bc25548 d25487bc .config console log report
ci-upstream-net-this-kasan-gce 2019/01/28 14:25 net abfd04f738c2 629c2a27 .config console log report
ci-upstream-net-this-kasan-gce 2019/01/15 12:53 net 2f960bd05640 ebacf5cb .config console log report
ci-upstream-net-this-kasan-gce 2019/01/13 10:39 net 8d008e64a2eb c3f3344c .config console log report
ci-upstream-net-this-kasan-gce 2019/01/04 21:08 net 96d4f267e40f 0127e3ba .config console log report
ci-upstream-net-kasan-gce 2019/02/07 04:28 net-next 5661f29ade24 d25487bc .config console log report
ci-upstream-net-kasan-gce 2019/02/04 07:45 net-next 9fb20801dab4 c198d5dd .config console log report
ci-upstream-net-kasan-gce 2019/01/03 22:19 net-next b71acb0e3721 66fcd29b .config console log report
ci-upstream-linux-next-kasan-gce-root 2019/03/03 00:36 linux-next c63e9e91a254 1c0e457a .config console log report
ci-upstream-linux-next-kasan-gce-root 2019/01/04 01:15 linux-next a4983672f9ca 7da23925 .config console log report
ci-upstream-linux-next-kasan-gce-root 2019/01/01 21:10 linux-next 6a1d293238c1 3d85f48c .config console log report
* Struck through repros no longer work on HEAD.