linux-kernel - [syzbot] [fs?] KCSAN: data-race in file_end_write / posix_acl_update

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Message-ID: <67f4e5e9.050a0220.396535.055c.GAE@google.com>
Date: Tue, 08 Apr 2025 02:01:29 -0700
From: syzbot <syzbot+dbb3b5b8e91c5be8daad@...kaller.appspotmail.com>
To: brauner@...nel.org, jack@...e.cz, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, 
	viro@...iv.linux.org.uk
Subject: [syzbot] [fs?] KCSAN: data-race in file_end_write / posix_acl_update_mode

Hello,

syzbot found the following issue on:

HEAD commit:    0af2f6be1b42 Linux 6.15-rc1
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c98070580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e5bf3e2a48bfe768
dashboard link: https://syzkaller.appspot.com/bug?extid=dbb3b5b8e91c5be8daad
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/d90ae40aa6df/disk-0af2f6be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/616ed7a70804/vmlinux-0af2f6be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ed2c418afc9a/bzImage-0af2f6be.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dbb3b5b8e91c5be8daad@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in file_end_write / posix_acl_update_mode

write to 0xffff888118513aa0 of 2 bytes by task 16080 on cpu 1:
 posix_acl_update_mode+0x220/0x250 fs/posix_acl.c:720
 simple_set_acl+0x6c/0x120 fs/posix_acl.c:1022
 set_posix_acl fs/posix_acl.c:954 [inline]
 vfs_set_acl+0x581/0x720 fs/posix_acl.c:1133
 do_set_acl+0xab/0x130 fs/posix_acl.c:1278
 do_setxattr fs/xattr.c:633 [inline]
 filename_setxattr+0x1f1/0x2b0 fs/xattr.c:665
 path_setxattrat+0x28a/0x320 fs/xattr.c:713
 __do_sys_setxattr fs/xattr.c:747 [inline]
 __se_sys_setxattr fs/xattr.c:743 [inline]
 __x64_sys_setxattr+0x6e/0x90 fs/xattr.c:743
 x64_sys_call+0x28e7/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:189
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888118513aa0 of 2 bytes by task 16073 on cpu 0:
 file_end_write+0x1f/0x110 include/linux/fs.h:3059
 vfs_fallocate+0x3a5/0x3b0 fs/open.c:350
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0x78/0xc0 fs/open.c:365
 x64_sys_call+0x295f/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:286
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x8000 -> 0x8072

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 16073 Comm: syz.6.3255 Not tainted 6.15.0-rc1-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


---
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