linux-kernel - [syzbot] [kernfs?] KCSAN: data-race in kernfs_iop_permission / kernfs_iop

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Message-ID: <0000000000000a4d6d061c6d0688@google.com>
Date: Thu, 04 Jul 2024 07:47:18 -0700
From: syzbot <syzbot+4d9e77bc73d118c6dc78@...kaller.appspotmail.com>
To: gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, tj@...nel.org
Subject: [syzbot] [kernfs?] KCSAN: data-race in kernfs_iop_permission /
 kernfs_iop_permission (4)

Hello,

syzbot found the following issue on:

HEAD commit:    22a40d14b572 Linux 6.10-rc6
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=140ac085980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
dashboard link: https://syzkaller.appspot.com/bug?extid=4d9e77bc73d118c6dc78
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ebe2f3933faf/disk-22a40d14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7227032da0fe/vmlinux-22a40d14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a330dc1e107b/bzImage-22a40d14.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4d9e77bc73d118c6dc78@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in kernfs_iop_permission / kernfs_iop_permission

write to 0xffff8881040ba060 of 8 bytes by task 11628 on cpu 0:
 inode_set_atime_to_ts include/linux/fs.h:1557 [inline]
 set_inode_attr fs/kernfs/inode.c:162 [inline]
 kernfs_refresh_inode fs/kernfs/inode.c:177 [inline]
 kernfs_iop_permission+0x118/0x220 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:461 [inline]
 inode_permission+0x18c/0x300 fs/namei.c:528
 may_lookup fs/namei.c:1726 [inline]
 link_path_walk+0x1b8/0x810 fs/namei.c:2273
 path_lookupat+0x72/0x2b0 fs/namei.c:2492
 filename_lookup+0x127/0x300 fs/namei.c:2522
 user_path_at_empty+0x42/0x120 fs/namei.c:2929
 user_path_at include/linux/namei.h:58 [inline]
 ksys_umount fs/namespace.c:1916 [inline]
 __do_sys_umount fs/namespace.c:1924 [inline]
 __se_sys_umount fs/namespace.c:1922 [inline]
 __x64_sys_umount+0x88/0xe0 fs/namespace.c:1922
 x64_sys_call+0x3af/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:167
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff8881040ba060 of 8 bytes by task 11589 on cpu 1:
 inode_set_atime_to_ts include/linux/fs.h:1557 [inline]
 set_inode_attr fs/kernfs/inode.c:162 [inline]
 kernfs_refresh_inode fs/kernfs/inode.c:177 [inline]
 kernfs_iop_permission+0x118/0x220 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:461 [inline]
 inode_permission+0x18c/0x300 fs/namei.c:528
 may_lookup fs/namei.c:1726 [inline]
 link_path_walk+0x1b8/0x810 fs/namei.c:2273
 path_parentat fs/namei.c:2540 [inline]
 __filename_parentat+0x13c/0x3c0 fs/namei.c:2564
 filename_parentat fs/namei.c:2582 [inline]
 do_unlinkat+0x9b/0x4c0 fs/namei.c:4382
 __do_sys_unlink fs/namei.c:4455 [inline]
 __se_sys_unlink fs/namei.c:4453 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4453
 x64_sys_call+0x28a3/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000030ac424b -> 0x0000000000a4528a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11589 Comm: syz-executor Not tainted 6.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================


---
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