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IDProjectCategoryView StatusDate SubmittedLast Update
0001807graphvizGraph Librariespublic2010-01-30 12:162011-04-28 04:03
ReporterDavid Brown 
Assigned Togviz 
PlatformOSx86-Windows-7OS Version
Summary0001807: Possible memory corruption when agmemread fails

I've only encountered this a couple of times. Sometimes I can reproduce
it and sometimes I can't, which I realize makes it difficult for you to
fix. Regardless, I'm filing this bug anyway, in case it comes up again or
by some miracle, you're able to reproduce it, as well.

I'm also not a C programmer, which probably limits the amount of relevant
information I can provide, but I understand enough to read the Graphviz
source code and call C functions from other programming languages (in my
case, C#).

Essentially, it appears that if agmemread is called with invalid input
data, it corrupts memory. After an unknown number of calls, it begins
causing access violation errors (in C#, this results in an
AccessViolationException) even when the input data is valid.

I restarted my machine to get a clean slate and now it works fine. But,
I'm uncertain how many invalid calls I need to make until it starts
exhibiting these symptoms. In addition, once one application using
agmemread begins failing in this manner, every application on my machine
that uses agmemread also begins to fail. Although, I can't tell if this is
a coincidence or not.
Additional Information

i believe the parser may be attempting to recover and in this
situation it may try to fetch an unknown number of input tokens.

Doesn't the agmemread() discipline know the input buffer size?

TagsNo tags attached.
VERSION     2.26
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- Issue History
Date Modified Username Field Change
2011-04-28 04:03 user1 New Issue
2011-04-28 04:03 user1 Assigned To => user1

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