Commit 0463f7c9aad060fcd56e98d025ce16185279e2bc
2016-02-04T18:34:38
Prevent overread when decoding malformed JPEG The accelerated Huffman decoder was previously invoked if there were > 128 bytes in the input buffer. However, it is possible to construct a JPEG image with Huffman blocks > 430 bytes in length (http://stackoverflow.com/questions/2734678/jpeg-calculating-max-size). While such images are pathological and could never be created by a JPEG compressor, it is conceivable that an attacker could use such an artifially-constructed image to trigger an input buffer overrun in the libjpeg-turbo decompressor and thus gain access to some of the data on the calling program's heap. This patch simply increases the minimum buffer size for the accelerated Huffman decoder to 512 bytes, which should (hopefully) accommodate any possible input. This addresses a major issue (LJT-01-005) identified in a security audit by Cure53.