Security Code Review

Systematic checklist for reviewing C code for security vulnerabilities.

Review Checklist

Memory:

• All array accesses bounds-checked
• Integer overflow checked before allocation/indexing
• No use-after-free potential
• Strings null-terminated after operations

Input:

• All external input validated at trust boundary
• Path inputs canonicalized and checked
• No user data in format strings
• Lengths validated before use

Functions:

• No banned functions (strcpy, sprintf, gets, etc.)
• Buffer sizes passed to all string operations
• Return values checked

Secrets:

• No credentials in logs or error messages
• Config file permissions verified
• Secrets scrubbed from memory when done

Files:

• No TOCTOU races (access then open)
• Symlinks handled safely (O_NOFOLLOW)
• Temp files use mkstemp

Grep for red flags:

grep -rn 'strcpy\|sprintf\|gets\|strcat\|mktemp' src/
grep -rn 'printf.*%s.*user\|system(\|popen(' src/