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From: "Richard M. Stallman" <rms@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: image size limit?
Date: Wed, 12 Oct 2005 12:24:29 -0400	[thread overview]
Message-ID: <E1EPjP3-0007dR-7H@fencepost.gnu.org> (raw)
In-Reply-To: <87oe5v7q19.fsf@stupidchicken.com> (message from Chong Yidong on Tue, 11 Oct 2005 16:32:50 -0400)

    One place where we can set a limit is in x_create_x_image_and_pixmap,
    where we malloc a pixmap to store the image contents.  The data
    supplied to us by the external library is copied into this pixmap.  We
    could signal an error if width and height are too large.  However,
    this seems like closing the barn door after the horses have left --
    the external library will already have allocated a big chunk of
    memory.

Will it free that memory if Emacs decides to abort the operation?
If so, I think that still counts as a solution.  If not, I think
it is a bug in the library--so we should ask them to fix it.

Meanwhile, if these libraries do not have the feature of limiting the
memory they can use, I think they ought to have it.  That is a
necessary part of defending against invalid data.  A nonsensical image
that swallows all of memory is the equivalent of a denial-of-service
attack.  Good apps defend against that, and good libraries should be
designed to help apps defend against that.

Would you like to write to the developers of these libraries,
asking them nicely to add such a feature?

  parent reply	other threads:[~2005-10-12 16:24 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-10-11 20:32 image size limit? Chong Yidong
2005-10-11 21:19 ` Kevin Rodgers
2005-10-12 16:24 ` Richard M. Stallman [this message]
2005-10-12 17:40   ` Romain Francoise
2005-10-13 20:13     ` Richard M. Stallman
2005-10-14 13:02       ` Chong Yidong
2005-10-15 16:13         ` Richard M. Stallman
2005-10-15 18:33           ` Chong Yidong
2005-10-16 17:36             ` Richard M. Stallman
2005-10-16 22:27       ` Chong Yidong
2005-10-17 17:30         ` Richard M. Stallman
2005-10-17 21:56           ` Chong Yidong
2005-10-18  3:39             ` Richard M. Stallman
2005-10-18 14:33               ` Stefan Monnier
2005-10-19  8:35                 ` Kim F. Storm
2005-10-19 12:20                   ` David Kastrup
2005-10-19 12:45                     ` Chong Yidong
2005-10-19 20:17                       ` Richard M. Stallman
2005-10-19 12:51                     ` Kim F. Storm
2005-10-19 20:17                       ` Richard M. Stallman
2005-10-19 21:55                         ` Kim F. Storm
2005-10-19 13:27                 ` Miles Bader
2005-10-20  4:54                   ` Richard M. Stallman
2005-10-19  9:02             ` Eli Zaretskii

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