syzbot


KCSAN: data-race in dev_graft_qdisc / qdisc_lookup_rcu

Status: fixed on 2023/07/04 09:17
Subsystems: net
[Documentation on labels]
Fix commit: d636fc5dd692 net: sched: add rcu annotations around qdisc->qdisc_sleeping
First crash: 361d, last: 361d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in dev_graft_qdisc / qdisc_lookup_rcu

read to 0xffff8881286fc618 of 8 bytes by task 6928 on cpu 1:
 qdisc_lookup_rcu+0x192/0x2c0 net/sched/sch_api.c:331
 __tcf_qdisc_find+0x74/0x3c0 net/sched/cls_api.c:1174
 tc_get_tfilter+0x18f/0x990 net/sched/cls_api.c:2547
 rtnetlink_rcv_msg+0x7af/0x8c0 net/core/rtnetlink.c:6386
 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413
 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503
 ___sys_sendmsg net/socket.c:2557 [inline]
 __sys_sendmsg+0x1e3/0x270 net/socket.c:2586
 __do_sys_sendmsg net/socket.c:2595 [inline]
 __se_sys_sendmsg net/socket.c:2593 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff8881286fc618 of 8 bytes by task 6912 on cpu 0:
 dev_graft_qdisc+0x4f/0x80 net/sched/sch_generic.c:1115
 qdisc_graft+0x7d0/0xb60 net/sched/sch_api.c:1103
 tc_modify_qdisc+0x712/0xf10 net/sched/sch_api.c:1693
 rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6395
 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413
 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503
 ___sys_sendmsg net/socket.c:2557 [inline]
 __sys_sendmsg+0x1e3/0x270 net/socket.c:2586
 __do_sys_sendmsg net/socket.c:2595 [inline]
 __se_sys_sendmsg net/socket.c:2593 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6912 Comm: syz-executor.5 Not tainted 6.4.0-rc3-syzkaller-00190-g0d85b27b0cc6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/16/2023
==================================================================
syz-executor.5 (6912) used greatest stack depth: 10472 bytes left

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/05/26 18:21 upstream 0d85b27b0cc6 cf184559 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dev_graft_qdisc / qdisc_lookup_rcu
* Struck through repros no longer work on HEAD.