Re: [PATCH] buildid: validate page-backed file before parsing build ID

[Jinchao Wang]

On Tue, Dec 23, 2025 at 11:05:49AM -0800, Shakeel Butt wrote:
> Hi Jinchao,
> 
> On Tue, Dec 23, 2025 at 06:32:07PM +0800, Jinchao Wang wrote:
> > __build_id_parse() only works on page-backed storage.  Its helper paths
> > eventually call mapping->a_ops->read_folio(), so explicitly reject VMAs
> > that do not map a regular file or lack valid address_space operations.
> > 
> > Reported-by: syzbot+e008db2ac01e282550ee@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Jinchao Wang <wangjinchao600@xxxxxxxxx>
> 
> Check the previous discussion on this at
> https://lore.kernel.org/all/20251114193729.251892-1-ssranevjti@xxxxxxxxx/
> 
> The preferred solution was to use kernel_read() call instead of adding
> more such checks. Please check and test the patch at
> https://lore.kernel.org/20251222205859.3968077-1-shakeel.butt@xxxxxxxxx/
> 

Thanks for the pointer.

After reading the discussion and the patch, I agree with you.
I also tested your patch, it fixes:
https://syzkaller.appspot.com/bug?extid=e008db2ac01e282550ee