convertbmp: detect invalid file dimensions early (CVE-2018-6616) #1172
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width/length dimensions read from bmp headers are not necessarily valid. For instance they may have been maliciously set to very large values with the intention to cause DoS (large memory allocation, stack overflow). In these cases we want to detect the invalid size as early as possible. This commit introduces a counter which verifies that the number of written bytes corresponds to the advertized width/length. Fixes uclouvain#1059 (CVE-2018-6616).
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@rouault can you review this PR? It would help us a lot to have this fixed. Thanks! |
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width/length dimensions read from bmp headers are not necessarily valid. For instance they may have been maliciously set to very large values with the intention to cause DoS (large memory allocation, stack overflow). In these cases we want to detect the invalid size as early as possible.
This PR introduces a counter which verifies that the number of written bytes corresponds to the advertised width/length.
If advertised size and actual size don't match, we return false which basically aborts execution.
We might alternatively consider resizing the data array and continue the execution normally. Do you think this would be preferable ?
This PR fixes #1059.