Any Debug::Print line longer than 45 characters writes past its buffer

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
75/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
cpp
Domain
embedded-iot

Research direction

Start with the Debug::Print function and its 45-byte static buffer, where the snprintfEx call formats the text. The issue proposes clamping the terminating zero index to the buffer size; check that expression against the return value of snprintfEx before changing anything. Done means a line longer than 45 characters no longer writes past the buffer, and a short line still prints unchanged.

Written by the indexing model from the issue text.

Description

bug
  • What this is: Debug::Print formats text into a 45-byte static buffer with snprintfEx.
    • Problem: snprintfEx keeps counting characters past the buffer size, then writes the closing '\0' at that count. Debug::Print(1,1,"%s", someLongString) with a 100-character result writes a zero byte 55 bytes past the buffer, into other static data.
    • Fix: One line: buffer[writtenChars < size ? writtenChars : size - 1] = '\0';
Dominant language
C++
Stars
90
Forks
5
No merged PRs in 30d

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