Cap PNG dimensions to avoid memory exhaustion (OCU-01-016) - #216
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AayushKumar26 wants to merge 1 commit into
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Cap PNG dimensions to avoid memory exhaustion (OCU-01-016)#216AayushKumar26 wants to merge 1 commit into
AayushKumar26 wants to merge 1 commit into
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_cfImageReadPNG() loads interlaced PNGs all at once, allocating xsize*ysize*3 in one malloc. The existing checks only catch overflow of that product, not large-but-valid sizes, so a crafted interlaced PNG could request an enormous allocation from a small file. Cap each dimension at 283465 px (5 m at 1440 dpi), which keeps the size multiplication from overflowing; allocations still too large for the machine then fail gracefully at the existing malloc NULL check. Fixes OpenPrinting#215
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What this fixes
Fixes #215 (audit finding OCU-01-016).
_cfImageReadPNG()loads interlaced PNGs all at once, allocatingxsize * ysize * 3in a singlemalloc. The existing checks only catch integer overflow of that multiplication, not large-but-valid sizes, so a crafted interlaced PNG with huge dimensions can request an enormous allocation from a small compressed file and exhaust memory in the filter child. It's reachable through the normal PNG print path.The changes
CF_IMAGE_MAX_PIXELS(283465), the pixels-per-side for a 5m print at 1440 dpi, which covers the largest realistic print (5m-wide inkjets exist)._cfImageReadPNG()now rejects images whose width or height exceeds that.Bounding each dimension keeps the decoded-size multiplication from overflowing. Any allocation still too large for the machine then fails gracefully at the existing
mallocNULL check, so real PNGs keep printing and only unreasonable input is rejected.