Fix S0C4 in process_dd for multi-digit SPACE values#22
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mgrossmann merged 1 commit intomainfrom Mar 12, 2026
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The 0x83 sub-key handler used a hardcoded buf += 7, which only worked for single-digit SPACE values (e.g. 1,1,1). Multi-digit values like (600,100,200) use longer length-prefixed encodings, causing the parser to misalign and overflow stack buffers via DDK/DSNAMEK/SYSOUTK memcpy calls, corrupting R13 and triggering S0C4 on function return. Replace hardcoded advancement with a proper loop that follows length-prefixed values. Add bounds checking on memcpy lengths as defense in depth. Closes #21
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Summary
buf += 7in the0x83SPACE quantities handler to properly parse variable-length length-prefixed valuesRoot Cause
The
0x83sub-key encodes SPACE quantities as length-prefixed numeric strings. Single-digit values like(1,1,1)are 7 bytes total, but multi-digit values like(600,100,200)are 13 bytes. The hardcoded advancement misaligned the parser, causing stack buffer overflows and R13 corruption → S0C4.Test plan
mbtbulk build for a project with large SPACE values (e.g. FTPD withSPACE=(TRK,(600,100,200)))Closes #21