linux-kernel - Re: [PATCH 2/2] drm/i915: Fix incorrect error handling in shmem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <k53h44tbytos5tvvbg263qpbkl4xzjcsj35fmpzxxie7dn7z65@ombf4w6za4ui>
Date: Wed, 20 Aug 2025 16:03:44 -0100
From: Andi Shyti <andi.shyti@...nel.org>
To: Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc: 陈涛涛 Taotao Chen <chentaotao@...iglobal.com>, 
	"jani.nikula@...ux.intel.com" <jani.nikula@...ux.intel.com>, 
	"joonas.lahtinen@...ux.intel.com" <joonas.lahtinen@...ux.intel.com>, "tursulin@...ulin.net" <tursulin@...ulin.net>, 
	"airlied@...il.com" <airlied@...il.com>, "simona@...ll.ch" <simona@...ll.ch>, 
	"oe-lkp@...ts.linux.dev" <oe-lkp@...ts.linux.dev>, "lkp@...el.com" <lkp@...el.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>, "brauner@...nel.org" <brauner@...nel.org>, 
	"oliver.sang@...el.com" <oliver.sang@...el.com>
Subject: Re: [PATCH 2/2] drm/i915: Fix incorrect error handling in
 shmem_pwrite()

Hi Rodrigo,

...

> > @@ -441,12 +441,12 @@ shmem_pwrite(struct drm_i915_gem_object *obj,
> >  	written = file->f_op->write_iter(&kiocb, &iter);
> >  	BUG_ON(written == -EIOCBQUEUED);
> >  
> > -	if (written != size)
> > -		return -EIO;
> > -
> >  	if (written < 0)
> >  		return written;
> >  
> > +	if (written != size)
> > +		return -EIO;
> 
> That's awkward...
> 
> I mean, you are right that we cannot overwrite what is returned from the
> write_iter function. But perhaps this != check here should be before?
> 
> Or it at least deserves a comment in the code telling what's the intent
> here. why != size is -EIO... but it was already written :/

The check (written < 0) is completely useless after (written !=
size), so that I think the patch is correct.

Andi

> > +
> >  	return 0;
> >  }
> >  
> > -- 
> > 2.34.1