linux-kernel - Re: [syzbot] [mm?] KCSAN: data-race in generic_fillattr / shmem

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Message-ID: <000000000000874d270621995192@google.com>
Date: Sun, 08 Sep 2024 03:44:01 -0700
From: syzbot <syzbot+702361cf7e3d95758761@...kaller.appspotmail.com>
To: aha310510@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] KCSAN: data-race in generic_fillattr / shmem_mknod (2)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KCSAN: data-race in __fsnotify_parent / fsnotify_put_mark

==================================================================
BUG: KCSAN: data-race in __fsnotify_parent / fsnotify_put_mark

write to 0xffff888101229cf0 of 4 bytes by task 3493 on cpu 0:
 fsnotify_detach_connector_from_object fs/notify/mark.c:330 [inline]
 fsnotify_put_mark+0x2db/0x5d0 fs/notify/mark.c:393
 __do_sys_inotify_rm_watch fs/notify/inotify/inotify_user.c:819 [inline]
 __se_sys_inotify_rm_watch+0x105/0x180 fs/notify/inotify/inotify_user.c:793
 __x64_sys_inotify_rm_watch+0x31/0x40 fs/notify/inotify/inotify_user.c:793
 x64_sys_call+0x1ae0/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:256
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

read to 0xffff888101229cf0 of 4 bytes by task 3339 on cpu 1:
 fsnotify_object_watched fs/notify/fsnotify.c:198 [inline]
 __fsnotify_parent+0xd4/0x380 fs/notify/fsnotify.c:228
 fsnotify_parent include/linux/fsnotify.h:96 [inline]
 fsnotify_file include/linux/fsnotify.h:131 [inline]
 fsnotify_open include/linux/fsnotify.h:401 [inline]
 vfs_open+0x1be/0x1f0 fs/open.c:1096
 do_open fs/namei.c:3727 [inline]
 path_openat+0x1a1e/0x1f00 fs/namei.c:3886
 do_filp_open+0xf7/0x200 fs/namei.c:3913
 do_sys_openat2+0xab/0x120 fs/open.c:1416
 do_sys_open fs/open.c:1431 [inline]
 __do_sys_openat fs/open.c:1447 [inline]
 __se_sys_openat fs/open.c:1442 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1442
 x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

value changed: 0x00002008 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3339 Comm: syz-executor.2 Not tainted 6.11.0-rc6-syzkaller-00326-gd1f2d51b711a-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
==================================================================


Tested on:

commit:         d1f2d51b Merge tag 'clk-fixes-for-linus' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=169a589f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e81d40b0108ea8fe
dashboard link: https://syzkaller.appspot.com/bug?extid=702361cf7e3d95758761
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=142a589f980000