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Subject: |
possibly uninitialized variable in gif_load |
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Date: |
Sat, 12 Mar 2011 23:17:25 -0800 |
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User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.14) Gecko/20110223 Thunderbird/3.1.8 |
I found this problem by code inspection.
The following code in the Emacs trunk src/image.c's gif_load
function is suspicious, because it uses a variable transparent_p
that appears to be uninitialized in some cases:
boolean transparent_p;
...
for (i = 0; i < gif->SavedImages[ino].ExtensionBlockCount; i++)
if ((gif->SavedImages[ino].ExtensionBlocks[i].Function
== GIF_LOCAL_DESCRIPTOR_EXTENSION)
&& gif->SavedImages[ino].ExtensionBlocks[i].ByteCount == 4
/* Transparency enabled? */
&& gif->SavedImages[ino].ExtensionBlocks[i].Bytes[0] & 1)
{
transparent_p = 1;
...
}
...
if (gif_color_map)
for (i = 0; i < gif_color_map->ColorCount; ++i)
{
if (transparent_p && transparency_color_index == i)
The code never sets transparent_p to any value other than 1,
but sometimes transparent_p appears to be uninitialized.
I'm filing a bug report so that someone who is more expert in this
code can take a look at it. In the meantime, I plan to work around
the problem by initializing the variable to 0.
I'm CC'ing this to Julien Danjou, who committed the code in question.
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--- Begin Message ---
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Subject: |
Re: possibly uninitialized variable in gif_load |
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Date: |
Sun, 13 Mar 2011 10:43:50 -0700 |
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User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.14) Gecko/20110223 Thunderbird/3.1.8 |
On 03/13/2011 03:27 AM, Julien Danjou wrote:
> Yeah, this should be the good fix AFAICS.
OK, thanks, I committed that as part of the merge to the
trunk in bzr 103644.
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