LibRaw: Out of bounds write in LibRaw::pana_data

### Summary Memory corruption can be achieved by parsing a RAW picture containing malicious Leaf metadata. ### Severity High - The values written out of bounds are read directly from the input and the size of the overflow is controllable by the length of the input file. If the target binary is compiled with the “-DLIBRAW_NOTHREADS” flag, the overflow manifests in stack memory; without such a flag it manifests in heap memory. ### Proof of Concept 1. Compile LibRaw following the instructions on https://github.com/LibRaw/LibRaw/blob/0.21.2/INSTALL 2. Run the `bin/simple_dcraw` sample binary with the provided file: bin/simple_dcraw [poc.bin](https://github.com/google/security-research/blob/master/pocs/LibRaw/IntegerWrapAroundPOC.bin) ### Further Analysis LibRaw allows the input file to contain metadata commonly used by different vendors, so it is possible to induce it into recognizing an input file as a Panasonic RAW picture by including a combination of TIFF tags. Among the supported TIFF tags, LibRaw supports metadata in the Leaf format. Such metadata is identified by a 0x8606 TIFF tag and it is handled by the `LibRaw::parse_mos` function. Along with other fields, it is possible to control the `load_flags` variable via a `Rows_data` entry: https://github.com/LibRaw/LibRaw/blob/0.21.2/src/metadata/mediumformat.cpp#L514 `load_flags` is an interesting variable: it is used in `LibRaw::pana_data` to limit how many bytes are copied - at most - from the input file, and at which offset into a target buffer, in case it is recognized by LibRaw as a Panasonic RAW picture: https://github.com/LibRaw/LibRaw/blob/0.21.2/src/decoders/decoders_dcraw.cpp#L1102 By specifying `load_flags` greater than 0x4000 it is possible to make the result of the subtraction wraparound and write outside of the destination buffer bounds: `LibRaw::fread` will try to read up to a huge amount of bytes into a buffer `buf` of size 0x4002. Such a buffer is allocated on the stack if the target binary is compiled with the “-DLIBRAW_NOTHREADS” flag, otherwise in the heap. ### Timeline **Date reported**: 09/13/2024 **Date fixed**: 09/18/2024 **Date disclosed**: 10/18/2024

Severity from

GitHub (reviewed advisory)

• github.com/google/security-research/security/advisories/GHSA-3m8c-vvxw-r44w
• github.com/google/security-research