syzbot


KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn (2)

Status: auto-closed as invalid on 2020/10/28 20:02
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 902d, last: 867d
similar bugs (3):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn 4 952d 963d 0/24 auto-closed as invalid on 2020/08/04 06:35
upstream KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn (4) 12 249d 420d 0/24 auto-closed as invalid on 2022/07/08 11:31
upstream KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn (3) 12 673d 770d 0/24 auto-closed as invalid on 2021/05/17 09:01

Sample crash report:
IPVS: ftp: loaded support on port[0] = 21
==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn

write to 0xffffffff8952501c of 4 bytes by task 12 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:558 [inline]
 pcpu_chunk_populated mm/percpu.c:1492 [inline]
 __pcpu_balance_workfn mm/percpu.c:2033 [inline]
 pcpu_balance_workfn+0xc6c/0xe30 mm/percpu.c:2069
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffffffff8952501c of 4 bytes by task 15306 on cpu 1:
 pcpu_alloc+0xb36/0x1370 mm/percpu.c:1835
 __alloc_percpu+0x20/0x30 mm/percpu.c:1907
 ipv6_init_mibs net/ipv6/af_inet6.c:900 [inline]
 inet6_net_init+0x284/0x440 net/ipv6/af_inet6.c:958
 ops_init+0x1e8/0x230 net/core/net_namespace.c:151
 setup_net+0x11b/0x630 net/core/net_namespace.c:341
 copy_net_ns+0x24c/0x390 net/core/net_namespace.c:482
 create_new_namespaces+0x216/0x520 kernel/nsproxy.c:110
 copy_namespaces+0x114/0x180 kernel/nsproxy.c:179
 copy_process+0x12ce/0x2dc0 kernel/fork.c:2072
 _do_fork+0x14a/0x6c0 kernel/fork.c:2428
 __do_sys_clone kernel/fork.c:2545 [inline]
 __se_sys_clone kernel/fork.c:2529 [inline]
 __x64_sys_clone+0xc8/0xf0 kernel/fork.c:2529
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15306 Comm: syz-executor.2 Not tainted 5.9.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (3):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci2-upstream-kcsan-gce 2020/09/23 19:54 upstream 805c6d3c1921 54289b08 .config console log report info
ci2-upstream-kcsan-gce 2020/09/17 08:36 upstream 5925fa68fe82 8247808b .config console log report info
ci2-upstream-kcsan-gce 2020/08/20 00:47 upstream 18445bf405cb ed282a3a .config console log report
* Struck through repros no longer work on HEAD.