libcupsfilters-tests: CUPS is a standards-based, open-source printing system, and`libcupsfilters` contains the code of the filters of the f...

CUPS is a standards-based, open-source printing system, and`libcupsfilters` contains the code of the filters of the former`cups-filters` package as library functions to be used for the data formatconversion tasks needed in Printer Applications. In CUPS-Filters versionsup to and including 1.28.17 and libscupsfilters versions 2.0.0 through2.1.1, CUPS-Filters's `imagetoraster` filter has an out of boundsread/write vulnerability in the processing of TIFF image files. While thepixel buffer is allocated with the number of pixels times a pre-calculatedbytes-per-pixel value, the function which processes these pixels is calledwith a size of the number of pixels times 3. When suitable inputs arepassed, the bytes-per-pixel value can be set to 1 and bytes outside of thebuffer bounds get processed. In order to trigger the bug, an attacker mustissue a print job with a crafted TIFF file, and pass appropriate print joboptions to control the bytes-per-pixel value of the output format. Theymust choose a printer configuration under which the `imagetoraster` filteror its C-function equivalent `cfFilterImageToRaster()` gets invoked. Thevulnerability exists in both CUPS-Filters 1.x and the successor librarylibcupsfilters (CUPS-Filters 2.x). In CUPS-Filters 2.x, the vulnerablefunction is `_cfImageReadTIFF() in libcupsfilters`. When this function isinvoked as part of `cfFilterImageToRaster()`, the caller passes alook-up-table during whose processing the out of bounds memory accesshappens. In CUPS-Filters 1.x, the equivalent functions are all found in thecups-filters repository, which is not split into subprojects yet, and thevulnerable code is in `_cupsImageReadTIFF()`, which is called through`cupsImageOpen()` from the `imagetoraster` tool. A patch is available incommit b69dfacec7f176281782e2f7ac44f04bf9633cfa.

Where it's fixed