syzbot


KCSAN: data-race in drop_sysctl_table / proc_sys_delete

Status: moderation: reported on 2024/03/25 04:26
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+3f1399b5c5759d00d3d2@syzkaller.appspotmail.com
First crash: 19d, last: 19d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in drop_sysctl_table / proc_sys_delete

write to 0xffff88815b7a1418 of 8 bytes by task 27126 on cpu 0:
 start_unregistering fs/proc/proc_sysctl.c:301 [inline]
 drop_sysctl_table+0x97/0x290 fs/proc/proc_sysctl.c:1498
 drop_sysctl_table+0x1ef/0x290 fs/proc/proc_sysctl.c:1505
 unregister_sysctl_table+0x30/0x50 fs/proc/proc_sysctl.c:1523
 unregister_net_sysctl_table+0x15/0x20 net/sysctl_net.c:185
 __devinet_sysctl_unregister net/ipv4/devinet.c:2612 [inline]
 devinet_sysctl_unregister net/ipv4/devinet.c:2640 [inline]
 inetdev_destroy net/ipv4/devinet.c:328 [inline]
 inetdev_event+0x614/0xb10 net/ipv4/devinet.c:1628
 notifier_call_chain kernel/notifier.c:93 [inline]
 raw_notifier_call_chain+0x6f/0x1d0 kernel/notifier.c:461
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:1950
 call_netdevice_notifiers_extack net/core/dev.c:1988 [inline]
 call_netdevice_notifiers net/core/dev.c:2002 [inline]
 unregister_netdevice_many_notify+0x83c/0xf20 net/core/dev.c:11099
 unregister_netdevice_many net/core/dev.c:11157 [inline]
 unregister_netdevice_queue+0x1f4/0x220 net/core/dev.c:11036
 unregister_netdevice include/linux/netdevice.h:3115 [inline]
 lapbeth_free_device drivers/net/wan/lapbether.c:437 [inline]
 lapbeth_device_event+0x47d/0x6d0 drivers/net/wan/lapbether.c:472
 notifier_call_chain kernel/notifier.c:93 [inline]
 raw_notifier_call_chain+0x6f/0x1d0 kernel/notifier.c:461
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:1950
 call_netdevice_notifiers_extack net/core/dev.c:1988 [inline]
 call_netdevice_notifiers net/core/dev.c:2002 [inline]
 unregister_netdevice_many_notify+0x83c/0xf20 net/core/dev.c:11099
 unregister_netdevice_many net/core/dev.c:11157 [inline]
 unregister_netdevice_queue+0x1f4/0x220 net/core/dev.c:11036
 unregister_netdevice include/linux/netdevice.h:3115 [inline]
 nsim_destroy+0x7d/0x130 drivers/net/netdevsim/netdev.c:456
 __nsim_dev_port_del+0xcd/0x100 drivers/net/netdevsim/dev.c:1425
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1437 [inline]
 nsim_dev_reload_destroy+0x1a6/0x2d0 drivers/net/netdevsim/dev.c:1658
 nsim_drv_remove+0x3e/0x100 drivers/net/netdevsim/dev.c:1673
 nsim_bus_remove+0x15/0x20 drivers/net/netdevsim/bus.c:398
 device_remove drivers/base/dd.c:566 [inline]
 __device_release_driver drivers/base/dd.c:1270 [inline]
 device_release_driver_internal+0x2e5/0x4f0 drivers/base/dd.c:1293
 device_release_driver+0x19/0x20 drivers/base/dd.c:1316
 bus_remove_device+0x26f/0x290 drivers/base/bus.c:574
 device_del+0x370/0x7b0 drivers/base/core.c:3894
 device_unregister+0x15/0x40 drivers/base/core.c:3935
 nsim_bus_dev_del drivers/net/netdevsim/bus.c:462 [inline]
 del_device_store+0x1cb/0x230 drivers/net/netdevsim/bus.c:226
 bus_attr_store+0x54/0x70 drivers/base/bus.c:170
 sysfs_kf_write+0xae/0xd0 fs/sysfs/file.c:136
 kernfs_fop_write_iter+0x1ce/0x2c0 fs/kernfs/file.c:334
 call_write_iter include/linux/fs.h:2108 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0x771/0x8e0 fs/read_write.c:590
 ksys_write+0xeb/0x1b0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:652
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

read to 0xffff88815b7a1418 of 8 bytes by task 2818 on cpu 1:
 proc_sys_delete+0x30/0x40 fs/proc/proc_sysctl.c:890
 retain_dentry fs/dcache.c:696 [inline]
 fast_dput+0x200/0x2b0 fs/dcache.c:799
 dput+0x24/0xd0 fs/dcache.c:839
 path_put fs/namei.c:561 [inline]
 terminate_walk+0xfb/0x280 fs/namei.c:685
 path_openat+0x1805/0x1d80 fs/namei.c:3800
 do_filp_open+0xf7/0x200 fs/namei.c:3826
 do_sys_openat2+0xab/0x120 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1432
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x0000000000000000 -> 0xffffffffffffffea

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2818 Comm: dhcpcd Not tainted 6.8.0-syzkaller-13236-g5e74df2f8f15 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/03/25 04:25 upstream 5e74df2f8f15 0ea90952 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in drop_sysctl_table / proc_sys_delete
* Struck through repros no longer work on HEAD.