base64: fix out-of-bounds write in htp_base64_decode #461
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The htp_base64_decode function previously performed a write to the output buffer (*plainchar) to store the partial result of the next byte before verifying if the output buffer had sufficient space. This resulted in a heap-buffer-overflow when the provided output buffer was undersized or exactly full. This patch fixes the issue by: 1. Moving the partial byte assignment after the buffer length check. 2. Correctly updating the decoder state (decoder->step and decoder->plainchar) when the buffer limit is reached, ensuring the state is preserved without writing out-of-bounds. Fixes OISF#458
Author
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Hi @catenacyber, please take a look |
Contributor
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Thanks for the work. |
Author
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Hi @catenacyber, thanks for your review, I've added several tests. The patched version passes all of them, while the unpatched version triggers an ASan error on each of them. |
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The htp_base64_decode function previously performed a write to the output buffer (*plainchar) to store the partial result of the next byte before verifying if the output buffer had sufficient space. This resulted in a heap-buffer-overflow when the provided output buffer was undersized or exactly full.
This patch fixes the issue by:
Fixes #458
This patch is generated by ASKRepair, an agentic automated vulnerability repair framework