linux-kernel - Re: [syzbot] [trace?] WARNING in write_raw_marker_to

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Message-Id: <20251012122648.d6ca8923c4ef5bc9fc483e9f@kernel.org>
Date: Sun, 12 Oct 2025 12:26:48 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: syzbot <syzbot+9a2ede1643175f350105@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 mathieu.desnoyers@...icios.com, rostedt@...dmis.org,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [trace?] WARNING in write_raw_marker_to_buffer

Hi,


This happens because we replaced (non field size check)
copy_from_user_nofault() to memcpy. So I think we need a cast
to void * there.

On Fri, 10 Oct 2025 14:00:37 -0700
syzbot <syzbot+9a2ede1643175f350105@...kaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    5472d60c129f Merge tag 'trace-v6.18-2' of git://git.kernel..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1239b458580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e7dba95d4cdd903c
> dashboard link: https://syzkaller.appspot.com/bug?extid=9a2ede1643175f350105
> compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15eec52f980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=122e9892580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/fbf444614257/disk-5472d60c.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/f129612e3b8b/vmlinux-5472d60c.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/8095ae997ffa/bzImage-5472d60c.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+9a2ede1643175f350105@...kaller.appspotmail.com
> 
> ------------[ cut here ]------------
> memcpy: detected field-spanning write (size 2655) of single field "&entry->id" at kernel/trace/trace.c:7458 (size 4)
> WARNING: CPU: 0 PID: 6004 at kernel/trace/trace.c:7458 write_raw_marker_to_buffer.isra.0+0x2d4/0x330 kernel/trace/trace.c:7458
> Modules linked in:
> CPU: 0 UID: 0 PID: 6004 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
> RIP: 0010:write_raw_marker_to_buffer.isra.0+0x2d4/0x330 kernel/trace/trace.c:7458
> Code: ff e8 30 74 fa ff c6 05 b4 7e aa 0e 01 90 b9 04 00 00 00 48 c7 c2 e0 1e 93 8b 4c 89 e6 48 c7 c7 40 1f 93 8b e8 6d fc b8 ff 90 <0f> 0b 90 90 e9 d7 fe ff ff e8 6e 04 62 00 e9 da fd ff ff e8 64 04
> RSP: 0018:ffffc90003837c40 EFLAGS: 00010282
> RAX: 0000000000000000 RBX: ffff88813ff34018 RCX: ffffffff817a5e58
> RDX: ffff888031d73c80 RSI: ffffffff817a5e65 RDI: 0000000000000001
> RBP: ffff88813ff34010 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000a5f
> R13: ffff88813ff18c00 R14: 0000000000000000 R15: 0000200000000040
> FS:  000055558e5ff500(0000) GS:ffff8881249e6000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b30263fff CR3: 0000000034638000 CR4: 00000000003526f0
> Call Trace:
>  <TASK>
>  tracing_mark_raw_write+0x2da/0x4a0 kernel/trace/trace.c:7500
>  vfs_write+0x2a0/0x11d0 fs/read_write.c:684
>  ksys_write+0x1f8/0x250 fs/read_write.c:738
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f18a0b8eec9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fff2b2d2c28 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007f18a0de5fa0 RCX: 00007f18a0b8eec9
> RDX: 0000000000000a5f RSI: 0000200000000040 RDI: 0000000000000003
> RBP: 00007f18a0c11f91 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f18a0de5fa0 R14: 00007f18a0de5fa0 R15: 0000000000000003
>  </TASK>
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>