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Date:   Fri, 21 Apr 2023 07:33:51 -0700
Message-ID: <000000000000be9fa205f9d98b5b@google.com>
Subject: [syzbot] [kernel?] KCSAN: data-race in complete_signal /
 do_group_exit (7)
From:   syzbot <syzbot+0864692611e2ae4cc85f@syzkaller.appspotmail.com>
To:     brauner@kernel.org, linux-kernel@vger.kernel.org,
        syzkaller-bugs@googlegroups.com
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Hello,

syzbot found the following issue on:

HEAD commit:    3a93e40326c8 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1769d1dec80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f7350c77b8056a38
dashboard link: https://syzkaller.appspot.com/bug?extid=0864692611e2ae4cc85f
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2122926bc9fe/disk-3a93e403.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8392992358bc/vmlinux-3a93e403.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6398a2d19a7e/bzImage-3a93e403.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0864692611e2ae4cc85f@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in complete_signal / do_group_exit

write to 0xffff88810491e534 of 4 bytes by task 13425 on cpu 0:
 complete_signal+0x541/0x6d0 kernel/signal.c:1053
 __send_signal_locked+0x5cc/0x700 kernel/signal.c:1190
 send_signal_locked+0x28d/0x3a0 kernel/signal.c:1253
 do_send_sig_info+0x9f/0xf0 kernel/signal.c:1296
 send_sig_info kernel/signal.c:1636 [inline]
 send_sig+0x53/0x60 kernel/signal.c:1646
 pipe_write+0x8b1/0xd70 fs/pipe.c:482
 call_write_iter include/linux/fs.h:1851 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x45a/0x750 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88810491e534 of 4 bytes by task 13410 on cpu 1:
 do_group_exit+0x3e/0x150 kernel/exit.c:998
 __do_sys_exit_group kernel/exit.c:1030 [inline]
 __se_sys_exit_group kernel/exit.c:1028 [inline]
 __x64_sys_exit_group+0x1f/0x20 kernel/exit.c:1028
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000002 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13410 Comm: syz-executor.0 Not tainted 6.3.0-rc4-syzkaller-00025-g3a93e40326c8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
==================================================================


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