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5th Underhanded C Contest Now Open

Posted by CmdrTaco on from the i-c-what-you've-done-there dept.

Xcott Craver writes "The next Underhanded C Contest has begun, with a deadline of March 1st. The object of the contest is to write short, readable, clear and innocent C code that somehow commits an evil act. This year's challenge: write a luggage routing program that mysteriously misroutes a customer's bag if a check-in clerk places just the right kind of text in a comment field. The prize is a gift certificate to ThinkGeek.com."

2 of 162 comments (clear)

  1. Possibilities by Rei · · Score: 3, Interesting

    I don't have the time for something like this, but it seems to me a good possibility would be to have all of your inputs that the clerk fills out be contiguous in memory, including the destination, have the algorithm to figure out what destination to go to scan through the whole destination string looking for matches (rather than looking for an exact match) and taking the last one it finds, and have a broken bounds check for the length of that string so that the algorithm looks into the comments section as well.

    So, for example, if the clerk fills out the destination as "LAX" but writes in the comments section, "Do not confuse his bags with those owned by CID who is also going to a different final destination; they're very similar looking.", the bags would be routed to Cedar Rapids (CID) instead of Los Angeles (LAX).

    --
    As it says in the Constitution, Lenin is in my shower.
  2. Re:I'm really impressed by troll8901 · · Score: 5, Interesting

    Here's some points I'd like to highlight, from the 2008 Winners.

    • Linus Akesson: The BYTESPERPIXEL macro "gives the false impression that the code intelligently supports higher bit widths" but actually "causes the 8-bit case to leak information into the file" (by exploiting a buffer overflow). ... (thus allowing wiped image data to be reconstructed.)
    • Avinash Baliga: The ExpectTrue macro overwrites the image mask (by exploiting a buffer overflow), allowing two bits to survive the wiping, (thus allowing wiped image data to be reconstructed). Furthermore, the evil behavior is concealed in an innocent-looking error checking macro.
    • John Meacham: (Winner) The code is "extremely simple, innocent, obvious" ... and devious. "Low-intensity pixels are replaced with a ‘0, and high-intensity pixels replaced with a ‘00 or a ‘000" ... (thus allowing wiped image data to be reconstructed.)

    All I can say is, Wow.