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More guards against invalid object file patch data

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This commit is contained in:
Rangi
2026-07-13 17:47:38 -04:00
parent 4a6ea35299
commit f0419eb183
1 changed files with 39 additions and 16 deletions
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src/link/patch.cpp
+39 -16
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@@ -291,7 +291,16 @@ static int32_t computeRPNExpr(Patch const &patch, std::vector<Symbol> const &fil
isError = true;
value = 1;
} else if (std::holds_alternative<Label>(symbol->data)) {
value = std::get<Label>(symbol->data).section->bank;
if (Label const &label = std::get<Label>(symbol->data); !label.section) {
errorAt(
patch,
"Requested `BANK()` of label `%s` outside of a section",
fileSymbols[symID].name.c_str()
);
value = 0;
} else {
value = label.section->bank;
}
} else {
errorAt(
patch,
@@ -449,8 +458,16 @@ static int32_t computeRPNExpr(Patch const &patch, std::vector<Symbol> const &fil
value = 0;
isError = true;
} else if (std::holds_alternative<Label>(symbol->data)) {
Label const &label = std::get<Label>(symbol->data);
value = label.section->org + label.offset;
if (Label const &label = std::get<Label>(symbol->data); !label.section) {
errorAt(
patch,
"Requested value of label `%s` outside of a section",
fileSymbols[symID].name.c_str()
);
value = 0;
} else {
value = label.section->org + label.offset;
}
} else {
value = std::get<int32_t>(symbol->data);
}
@@ -568,21 +585,27 @@ static void applyFilePatches(Section &section, Section &dataSection) {
dataSection.name.c_str(),
dataSection.data.size()
);
} else if (patch.type == PATCHTYPE_JR) { // `jr` is quite unlike the others...
// Offset is relative to the byte *after* the operand
// PC as operand to `jr` is lower than reference PC by 2
uint16_t address = patch.pcSection->org + patch.pcOffset + 2;
int16_t jumpOffset = value - address;
} else if (patch.type == PATCHTYPE_JR) {
if (!patch.pcSection) {
errorAt(patch, "PC has no value outside of a section");
dataSection.data[offset] = 0;
isError = true;
} else {
// Offset is relative to the byte *after* the operand
// PC as operand to `jr` is lower than reference PC by 2
uint16_t address = patch.pcSection->org + patch.pcOffset + 2;
int16_t jumpOffset = value - address;
if (jumpOffset < -128 || jumpOffset > 127) {
firstErrorAt(
patch,
"`JR` target must be between -128 and 127 bytes away, not %" PRId16
"; use `JP` instead",
jumpOffset
);
if (jumpOffset < -128 || jumpOffset > 127) {
firstErrorAt(
patch,
"`JR` target must be between -128 and 127 bytes away, not %" PRId16
"; use `JP` instead",
jumpOffset
);
}
dataSection.data[offset] = jumpOffset & 0xFF;
}
dataSection.data[offset] = jumpOffset & 0xFF;
} else {
// Patch a certain number of bytes
if (typeSize < sizeof(int)) {