Fix heap buffer overflow in pnm2png due to integer overflow in row_bytes - #823
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Fix heap buffer overflow in pnm2png due to integer overflow in row_bytes#823VinzSpring wants to merge 1 commit into
VinzSpring wants to merge 1 commit into
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The row_bytes calculation (width * channels * bytes_per_sample) could silently wrap a uint32, bypassing the existing row_bytes == 0 guard and causing a heap buffer overflow. For example, a P6 PPM with width 1431655766 yields row_bytes = 2 after wrapping, allocating a 2-byte buffer while the write loop writes width*3 bytes. Add overflow detection before the multiplication for both the normal and packed-bitmap code paths. Fixes: pnggroup#794
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Consult #799 |
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closed in favor of pnggroup/pngcontrib#2 |
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Fixes a heap buffer overflow in
contrib/pngminus/pnm2png.ccaused by integer overflow in therow_bytescalculation, as reported in #794.The existing guard only catches
row_bytes == 0, so a wrapped value of 2 passes through. A 2-byte buffer is allocated viapng_malloc, but the write loop iterateswidth × channels = ~4.3 billionbytes, causing a heap buffer overflow confirmed by AddressSanitizer.Fixes #794