syzbot


divide error in tabledist

Status: fixed on 2019/10/15 23:40
Subsystems: net
[Documentation on labels]
Fix commit: b41d936b5ecf sch_netem: fix a divide by zero in tabledist()
First crash: 1736d, last: 1727d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream divide error in tabledist (2) C done error 39 1463d 1704d 0/27 closed as invalid on 2021/10/06 02:59
linux-4.19 divide error in tabledist C done 3 1342d 1699d 1/1 fixed on 2020/11/17 09:23

Sample crash report:
divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 14354 Comm: kworker/0:11 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events rt6_probe_deferred
RIP: 0010:tabledist.part.0+0x68/0x170 net/sched/sch_netem.c:335
Code: 00 00 00 00 00 fc ff df 48 c1 ea 03 0f b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 e6 00 00 00 31 d2 44 89 f0 <f7> 33 48 b8 00 00 00 00 00 fc ff df 48 8d 7c 53 04 48 89 f9 48 c1
RSP: 0018:ffff88809cfdf458 EFLAGS: 00010246
RAX: 000000001d99a220 RBX: ffff888068c33400 RCX: ffffffff833b54b4
RDX: 0000000000000000 RSI: ffffffff85c48c89 RDI: 0000000000000005
RBP: ffff88809cfdf480 R08: ffff88805d7aa440 R09: ffffed10139fbe7c
R10: ffffed10139fbe7b R11: 0000000000000003 R12: ffffffffb8bdc840
R13: 0000000000804100 R14: 000000001d99a220 R15: ffff888068374500
FS:  0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffe8066c4c CR3: 000000006c3b4000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tabledist net/sched/sch_netem.c:535 [inline]
 netem_enqueue+0x416/0x2d80 net/sched/sch_netem.c:535
 __dev_xmit_skb net/core/dev.c:3531 [inline]
 __dev_queue_xmit+0x157e/0x35b0 net/core/dev.c:3842
 dev_queue_xmit+0x18/0x20 net/core/dev.c:3906
 neigh_resolve_output net/core/neighbour.c:1490 [inline]
 neigh_resolve_output+0x5a5/0x970 net/core/neighbour.c:1470
 neigh_output include/net/neighbour.h:511 [inline]
 ip6_finish_output2+0x1034/0x2520 net/ipv6/ip6_output.c:116
 __ip6_finish_output+0x444/0xa50 net/ipv6/ip6_output.c:142
 ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152
 NF_HOOK_COND include/linux/netfilter.h:294 [inline]
 ip6_output+0x235/0x7c0 net/ipv6/ip6_output.c:175
 dst_output include/net/dst.h:436 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 ndisc_send_skb+0xf29/0x1450 net/ipv6/ndisc.c:505
 ndisc_send_ns+0x3a9/0x850 net/ipv6/ndisc.c:647
 rt6_probe_deferred+0xe3/0x1a0 net/ipv6/route.c:615
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace ecf873f6d17c08ac ]---
RIP: 0010:tabledist.part.0+0x68/0x170 net/sched/sch_netem.c:335
Code: 00 00 00 00 00 fc ff df 48 c1 ea 03 0f b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 e6 00 00 00 31 d2 44 89 f0 <f7> 33 48 b8 00 00 00 00 00 fc ff df 48 8d 7c 53 04 48 89 f9 48 c1
RSP: 0018:ffff88809cfdf458 EFLAGS: 00010246
RAX: 000000001d99a220 RBX: ffff888068c33400 RCX: ffffffff833b54b4
RDX: 0000000000000000 RSI: ffffffff85c48c89 RDI: 0000000000000005
RBP: ffff88809cfdf480 R08: ffff88805d7aa440 R09: ffffed10139fbe7c
R10: ffffed10139fbe7b R11: 0000000000000003 R12: ffffffffb8bdc840
R13: 0000000000804100 R14: 000000001d99a220 R15: ffff888068374500
FS:  0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffe8066c4c CR3: 000000006c3b4000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/09/28 12:10 net-next-old b41dae061bbd d8074e0b .config console log report ci-upstream-net-kasan-gce
2019/09/23 03:43 net-next-old b41dae061bbd d96e88f3 .config console log report ci-upstream-net-kasan-gce
2019/09/19 14:47 net-next-old b41dae061bbd eb940044 .config console log report ci-upstream-net-kasan-gce
* Struck through repros no longer work on HEAD.