From: boehm.igor@gmail.com
To: 9front@9front.org
Cc: boehm.igor@gmail.com
Subject: Re: [9front] drawterm: fix suicide caused by off-by-one write and out-of-bound read in libmemdraw/draw.c (patch)
Date: Sat, 06 Feb 2021 11:05:43 +0100 [thread overview]
Message-ID: <D383EF46640745E6129B36D77E1F8C7A@gmail.com> (raw)
In-Reply-To: <7D1FE3106BC07BB1AC2EC2F04FC1D349@eigenstate.org>
Quoth ori@eigenstate.org:
> Quoth boehm.igor@gmail.com:
> > for(i=0; i<dx; i++){
> > - u = r[0] | (r[1]<<8) | (r[2]<<16) | (r[3]<<24);
> > + for(j = 0, u = 0 ; j < 4 && r+j < end ; j++)
> > + u |= r[j] << (8*j);
> >
>
> This fix seems wrong: 'u = ...' is loading a pixel. Why
> would we ever want to load *half* a pixel?
>
> it seems like we either want to stop early, or ensure we
> allocate the right size image.
Thanks for reviewing Ori. Yeah, you are right.
Let me go back and study the code a bit more and try to come
up with something that is not a hack.
prev parent reply other threads:[~2021-02-06 10:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 21:19 boehm.igor
2021-02-05 21:18 ` ori
2021-02-06 10:05 ` boehm.igor [this message]
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