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How can one identify the full path (or the URL) of images producing

Bogus Huffman table definition
Bogus marker length

entries in the /var/log/httpd/error_log?

Can Apache be configured to be more verbose when logging this kind of errors?

Red Hat 4.1.2-52 system (Kernel 2.6.18), Apache 2.2.3, gd 2.0.34

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What code is doing the image manipulation? –  Shane Madden May 31 '12 at 16:59
    
I could only identify some PHP 5.2.16 scripts using gd2 library functions so far, but chances are there also are Java, Ruby and maybe more servlets/scripts involved. That's why I was hoping to find some general way to identify the buggy images. –  Jürgen Thelen May 31 '12 at 19:58
    
Can you correlate the timestamps on the error messages to entries in your access logs? –  Shane Madden May 31 '12 at 20:40
    
Unfortunately not. The "Bogus Huffman/marker" entries in the error_log do not contain timestamps (in contrast to all the other error_log entries). Other entries surrounding a "Bogus" entry let me reduce it to a known time span, but this time span ranges from several minutes up to hours, which means hundreds (if not thousands) of possible correlations to access_log entries. –  Jürgen Thelen May 31 '12 at 20:58
    
You could try cranking the error log's verbosity up with LogLevel debug, but that might be a little insane depending on how much traffic your server gets. –  Shane Madden May 31 '12 at 21:09

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