Unspecified vulnerability in certain versions of xpdf after 3.00, as used in various products including (a) pdfkit.framework, (b) gpdf, (c) pdftohtml, and (d) libextractor, has unknown impact and user-assisted attack vectors, possibly involving errors in (1) gmem.c, (2) SplashXPathScanner.cc, (3) JBIG2Stream.cc, (4) JPXStream.cc, and/or (5) Stream.cc. NOTE: this description is based on Debian advisory DSA 979, which is based on changes that were made after other vulnerabilities such as CVE-2006-0301 and CVE-2005-3624 through CVE-2005-3628 were fixed. Some of these newer fixes appear to be security-relevant, although it is not clear if they fix specific issues or are defensive in nature.

SuSE reported a buffer overflow in FoFiType1::parse affecting older xpdf versions. Code snippets from fofi/FoFiType1.cc:

133 void FoFiType1::parse() { ... 163 line = getNextLine(line); 164 for (j = 0; j < 300 && line; ++j) { 165 line1 = getNextLine(line); 166 if ((n = line1 - line) > 255) { 167 n = 255; 168 } 169 strncpy(buf, line, n);

getNextLine can, however, return NULL:

117 char FoFiType1::getNextLine(char line) { 118 while (line < (char )file + len && line != '\x0a' && line != '\x0d') { 119 ++line; 120 } 121 if (line < (char )file + len && line == '\x0d') { 122 ++line; 123 } 124 if (line < (char )file + len && line == '\x0a') { 125 ++line; 126 } 127 if (line >= (char )file + len) { 128 return NULL; 129 }

Therefore, (line1 - line) is not defined / results in negative value n. That value is later passed to strncpy, causing overflow of buf buffer.