KASAN: use-after-free Read in route4_get (2)

Status: upstream: reported C repro on 2021/09/12 17:58
Reported-by: syzbot+83fbd7715d9c3cbc9ef6@syzkaller.appspotmail.com
First crash: 1781d, last: 1751d
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 2300d 2329d 15/29 fixed on 2020/05/10 10:41
linux-4.14 KASAN: use-after-free Read in route4_get 19 syz error 3 2254d 2338d 0/1 upstream: reported syz repro on 2020/03/05 03:16
linux-4.19 KASAN: use-after-free Read in route4_get 19 7 2319d 2325d 0/1 auto-closed as invalid on 2020/07/22 04:44
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2021/11/12 06:52 16m bisect fix linux-4.19.y error job log
2021/10/13 06:09 35m bisect fix linux-4.19.y OK (0) job log log

Sample crash report:
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+0x3e1/0x420 net/sched/cls_route.c:239
Read of size 4 at addr ffff88809f730e40 by task syz-executor497/9517

CPU: 1 PID: 9517 Comm: syz-executor497 Not tainted 4.19.206-syzkaller #0
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+0x1fc/0x2ef lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load4_noabort+0x88/0x90 mm/kasan/report.c:432
 route4_get+0x3e1/0x420 net/sched/cls_route.c:239
 tc_new_tfilter+0x535/0x16c0 net/sched/cls_api.c:1300
 rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2457
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1911
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:661
 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227
 __sys_sendmsg net/socket.c:2265 [inline]
 __do_sys_sendmsg net/socket.c:2274 [inline]
 __se_sys_sendmsg net/socket.c:2272 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2272
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x449799
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 15 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f924dcaa318 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004cf508 RCX: 0000000000449799
RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000004
RBP: 00000000004cf500 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 000000000049e49c
R13: 00007ffcb51bdfdf R14: 00007f924dcaa400 R15: 0000000000022000

Allocated by task 9517:
 kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
 kmalloc include/linux/slab.h:515 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 route4_change+0x2a5/0x22a0 net/sched/cls_route.c:495
 tc_new_tfilter+0xb52/0x16c0 net/sched/cls_api.c:1320
 rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2457
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1911
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:661
 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227
 __sys_sendmsg net/socket.c:2265 [inline]
 __do_sys_sendmsg net/socket.c:2274 [inline]
 __se_sys_sendmsg net/socket.c:2272 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2272
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2888:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcc/0x210 mm/slab.c:3822
 route4_delete_filter_work+0x17/0x20 net/sched/cls_route.c:270
 process_one_work+0x864/0x1570 kernel/workqueue.c:2153
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

The buggy address belongs to the object at ffff88809f730e00
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 64 bytes inside of
 192-byte region [ffff88809f730e00, ffff88809f730ec0)
The buggy address belongs to the page:
page:ffffea00027dcc00 count:1 mapcount:0 mapping:ffff88813bff0040 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea00023dd9c8 ffffea00027bfe88 ffff88813bff0040
raw: 0000000000000000 ffff88809f730000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809f730d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809f730d80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88809f730e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88809f730e80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88809f730f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/09/13 06:09 linux-4.19.y b172b44fcb17 3ce60af8 .config console log report syz C ci2-linux-4-19 KASAN: use-after-free Read in route4_get
2021/09/12 17:57 linux-4.19.y b172b44fcb17 3ce60af8 .config console log report syz ci2-linux-4-19 KASAN: use-after-free Read in route4_get
* Struck through repros no longer work on HEAD.