KASAN: use-after-free Read in route4_get

Status: upstream: reported syz repro on 2020/03/05 03:16
Reported-by: syzbot+ba90f76265077c06c53b@syzkaller.appspotmail.com
First crash: 2337d, last: 2254d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in route4_get net 19 syz, C 8 2299d 2329d 15/29 fixed on 2020/05/10 10:41
linux-4.19 KASAN: use-after-free Read in route4_get (2) 19 syz, C error 2 1750d 1781d 0/1 upstream: reported C repro on 2021/09/12 17:58
linux-4.19 KASAN: use-after-free Read in route4_get 19 7 2318d 2325d 0/1 auto-closed as invalid on 2020/07/22 04:44
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2022/12/27 04:31 13m retest repro linux-4.14.y report log
2022/08/31 12:27 10m retest repro linux-4.14.y report log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2020/06/27 00:34 0m bisect fix linux-4.14.y error job log
2020/05/27 23:56 38m bisect fix linux-4.14.y OK (0) job log log
2020/04/27 23:18 38m bisect fix linux-4.14.y OK (0) job log log

Sample crash report:
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
==================================================================
BUG: KASAN: use-after-free in route4_get+0x2e6/0x320 net/sched/cls_route.c:242
Read of size 4 at addr ffff888080d9c240 by task syz-executor.5/8052

CPU: 0 PID: 8052 Comm: syz-executor.5 Not tainted 4.14.174-syzkaller #0
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+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393
 route4_get+0x2e6/0x320 net/sched/cls_route.c:242
 tc_ctl_tfilter+0xc04/0x18e6 net/sched/cls_api.c:689
 rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4315
 netlink_rcv_skb+0x127/0x370 net/netlink/af_netlink.c:2433
 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
 netlink_unicast+0x437/0x620 net/netlink/af_netlink.c:1313
 netlink_sendmsg+0x733/0xbe0 net/netlink/af_netlink.c:1878
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xc5/0x100 net/socket.c:656
 ___sys_sendmsg+0x70a/0x840 net/socket.c:2062
 __sys_sendmsg+0xa3/0x120 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007f8b261b4c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8b261b56d4 RCX: 000000000045c849
RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000006
RBP: 000000000076bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000009fd R14: 00000000004ccb4d R15: 000000000076bfac

Allocated by task 8047:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 kmem_cache_alloc_trace+0x14d/0x7b0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 route4_change+0x215/0x1c4d net/sched/cls_route.c:498
 tc_ctl_tfilter+0xf13/0x18e6 net/sched/cls_api.c:738
 rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4315
 netlink_rcv_skb+0x127/0x370 net/netlink/af_netlink.c:2433
 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
 netlink_unicast+0x437/0x620 net/netlink/af_netlink.c:1313
 netlink_sendmsg+0x733/0xbe0 net/netlink/af_netlink.c:1878
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xc5/0x100 net/socket.c:656
 ___sys_sendmsg+0x70a/0x840 net/socket.c:2062
 __sys_sendmsg+0xa3/0x120 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 7608:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 route4_delete_filter_work+0x17/0x20 net/sched/cls_route.c:272
 process_one_work+0x813/0x1540 kernel/workqueue.c:2116
 worker_thread+0x5d1/0x1070 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff888080d9c200
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 64 bytes inside of
 192-byte region [ffff888080d9c200, ffff888080d9c2c0)
The buggy address belongs to the page:
page:ffffea0002036700 count:1 mapcount:0 mapping:ffff888080d9c000 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff888080d9c000 0000000000000000 0000000100000010
raw: ffffea0002037ce0 ffffea00024354a0 ffff88812fe56040 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888080d9c100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888080d9c180: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888080d9c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888080d9c280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888080d9c300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/03/28 23:18 linux-4.14.y 01364dad1d45 f1ebdfba .config console log report syz ci2-linux-4-14
2020/03/19 13:30 linux-4.14.y 12cd844a39ed 2c31c529 .config console log report ci2-linux-4-14
2020/03/05 03:16 linux-4.14.y 78d697fc93f9 576fb9bc .config console log report ci2-linux-4-14
* Struck through repros no longer work on HEAD.