KASAN: use-after-free Read in xt_find_match

Status: upstream: reported C repro on 2020/09/11 02:31
First crash: 1322d, last: 476d
Fix bisection: failed (error log, bisect log)
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 KASAN: slab-out-of-bounds Read in xt_find_match C error 29 426d 1502d 0/1 upstream: reported C repro on 2020/03/15 05:47

Sample crash report:
audit: type=1400 audit(1599791312.209:8): avc:  denied  { execmem } for  pid=6450 comm="syz-executor444" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
IPVS: ftp: loaded support on port[0] = 21
BUG: KASAN: use-after-free in __lock_acquire+0x2cb4/0x3ff0 kernel/locking/lockdep.c:3294
Read of size 8 at addr ffff88809adb3520 by task syz-executor444/6451

CPU: 1 PID: 6451 Comm: syz-executor444 Not tainted 4.19.144-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/0x2fe lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
 __lock_acquire+0x2cb4/0x3ff0 kernel/locking/lockdep.c:3294
 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3907
 __mutex_lock_common kernel/locking/mutex.c:925 [inline]
 __mutex_lock+0xd7/0x1260 kernel/locking/mutex.c:1072
 xt_find_match net/netfilter/x_tables.c:189 [inline]
 xt_find_match+0xa3/0x280 net/netfilter/x_tables.c:181
 xt_request_find_match net/netfilter/x_tables.c:219 [inline]
 xt_request_find_match+0x88/0x110 net/netfilter/x_tables.c:212
 get_xt_match net/sched/em_ipt.c:112 [inline]
 em_ipt_change+0x1c7/0x46b net/sched/em_ipt.c:132
 tcf_em_validate net/sched/ematch.c:248 [inline]
 tcf_em_tree_validate net/sched/ematch.c:365 [inline]
 tcf_em_tree_validate+0x8fa/0xe95 net/sched/ematch.c:307
 flow_change+0x2a4/0x1ca0 net/sched/cls_flow.c:439
 tc_new_tfilter+0xb52/0x16c0 net/sched/cls_api.c:1320
 rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4778
 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:632
 ___sys_sendmsg+0x3b3/0x8e0 net/socket.c:2115
 __sys_sendmmsg+0x195/0x470 net/socket.c:2210
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2236
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
RIP: 0033:0x440d09
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 fb 0f fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe0791ee58 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004a2570 RCX: 0000000000440d09
RDX: 010efe10675dec16 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 00007ffe0791ee60 R08: 0000000120080522 R09: 0000000120080522
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004a2570
R13: 0000000000402220 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 1:
 kmem_cache_alloc+0x122/0x370 mm/slab.c:3559
 getname_flags+0xce/0x590 fs/namei.c:140
 do_sys_open+0x26c/0x520 fs/open.c:1079
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293

Freed by task 1:
 __cache_free mm/slab.c:3503 [inline]
 kmem_cache_free+0x7f/0x260 mm/slab.c:3765
 putname+0xe1/0x120 fs/namei.c:261
 do_sys_open+0x2ba/0x520 fs/open.c:1094
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293

The buggy address belongs to the object at ffff88809adb2900
 which belongs to the cache names_cache of size 4096
The buggy address is located 3104 bytes inside of
 4096-byte region [ffff88809adb2900, ffff88809adb3900)
The buggy address belongs to the page:
page:ffffea00026b6c80 count:1 mapcount:0 mapping:ffff8880aa00ab40 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea00026aad88 ffffea0002691488 ffff8880aa00ab40
raw: 0000000000000000 ffff88809adb2900 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809adb3400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809adb3480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809adb3500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809adb3580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809adb3600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/09/11 02:30 linux-4.19.y 67957f12548c ac7ca78e .config console log report syz C ci2-linux-4-19
2021/10/04 10:36 linux-4.19.y c2276d585654 ce697b49 .config console log report syz ci2-linux-4-19 KASAN: use-after-free Read in xt_find_match
2023/01/04 17:29 linux-4.19.y 3f8a27f9e27b 1dac8c7a .config console log report info [disk image] [vmlinux] ci2-linux-4-19 KASAN: use-after-free Read in xt_find_match
2022/06/18 12:50 linux-4.19.y 3f8a27f9e27b 8f633d84 .config console log report info ci2-linux-4-19 KASAN: use-after-free Read in xt_find_match
* Struck through repros no longer work on HEAD.