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Fedict / eid-mw

eID Middleware (main repository)
GNU Lesser General Public License v3.0
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Checking if `value_in > 63` when `value_in` can be signed. #167

Closed ViralTaco closed 2 years ago

ViralTaco commented 2 years ago

Hi, This is dangerous: https://github.com/Fedict/eid-mw/blob/9bd5d84ff7a550b5d4ec6ae5af6ad176f30a7685/plugins_tools/eid-viewer/b64/base64enc.c#L22

Consider replacing it with:

if ((unsigned char) value_in > 63) return '=';

This has well-defined behavior for all values of value_in.

Side note: value_in could be const but it doesn't really matter, here. NB: The assembly generated should be the same, with the JG (jump [short] if greater --> signed) being replaced with JA (jump [short] if above --> unsigned). (cf: Intel® 64 and IA-32 Architectures Software Developer's Manual Volume 2A: Instruction Set Reference, A-L 3-537 to 3-541)

Frederikus commented 2 years ago

Hello,

Indeed, thank you for reporting this out of bound issue.

We pushed a fix. May we add you to the Contributer list, and if so, under which name?

ViralTaco commented 2 years ago

Hi, You may add me, thank you. My name is Anthony Capobianco. For reference, the patch is commit 839852234086cdaaf9dbdf7019c29e7d97d61252.