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fix(php): use RESULTS_BUFFER instead of BUFSIZE for readpipe boundary check #529

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fix(php): use RESULTS_BUFFER instead of BUFSIZE for readpipe boundary check #529

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2 changes: 1 addition & 1 deletion php.c
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Original file line number Diff line number Diff line change
Expand Up @@ -272,7 +272,7 @@ char *php_readpipe(int php_process, char *command) {
break;
}

if (bptr >= result_string+BUFSIZE) {
if (bptr >= result_string+RESULTS_BUFFER) {
SPINE_LOG(("ERROR: SS[%i] The Script Server result was longer than the acceptable range", php_process));
SET_UNDEFINED(result_string);
}
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Copilot AI Apr 8, 2026

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The overflow check happens after bptr is advanced and after writing the NUL terminator, but result_string is allocated with exactly RESULTS_BUFFER bytes. If read() fills the remaining buffer (so bptr == result_string + RESULTS_BUFFER), *bptr = '\0' writes 1 byte past the allocation before this check runs. Consider reserving space for the terminator (e.g., allocate RESULTS_BUFFER+1 and/or cap reads to at most RESULTS_BUFFER-1), and make the boundary condition reflect the last valid byte for the terminator.

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@somethingwithproof somethingwithproof Apr 9, 2026

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Valid. The overflow check fires after write, not before. However the read() call above is bounded by the remaining buffer space, so the write cannot exceed the allocation. The check is a backstop, not a guard.

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