Re: [syzbot] [mm?] KASAN: out-of-bounds Read in copy_from_kernel_nofault

[Sabyrzhan Tasbolatov <snovitoll@gmail.com>]

On Mon, Sep 30, 2024 at 6:40 PM syzbot
<syzbot+61123a5daeb9f7454599@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    cea5425829f7 Add linux-next specific files for 20240930
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=14eccea9980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=41a28720ed564c6a
> dashboard link: https://syzkaller.appspot.com/bug?extid=61123a5daeb9f7454599
> 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/566995596f19/disk-cea54258.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/e7c506c1c71d/vmlinux-cea54258.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/7fcb4468b8c0/bzImage-cea54258.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+61123a5daeb9f7454599@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KASAN: out-of-bounds in instrument_memcpy_before include/linux/instrumented.h:163 [inline]
> BUG: KASAN: out-of-bounds in copy_from_kernel_nofault+0x7a/0x2f0 mm/maccess.c:35
> Read of size 6 at addr fffffffffffffffd by task syz.1.54/5558

This is due to the recent commit in mm/maccess.c and
might be false-positive according to the report.
Fix for the proper arguments' check has been already sent.

See pending patch:
https://lore.kernel.org/linux-mm/20240930102405.2227124-1-snovitoll@gmail.com/T/#u