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fix oob read in getSpelling when node has no ext tokens #8907

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fix oob read in getSpelling when node has no ext tokens #8907

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a3c8020
fix oob read in getSpelling when node has no ext tokens
Nussu06 Oct 1, 2026
9781751
clangimport: drop redundant per-branch typeIndex guards in getSpelling
Nussu06 Oct 2, 2026
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6 changes: 2 additions & 4 deletions lib/clangimport.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -422,15 +422,13 @@ std::string clangimport::AstNode::getSpelling() const
if (nodeType == FunctionDecl || nodeType == CXXConstructorDecl || nodeType == CXXMethodDecl) {
while (typeIndex >= 0 && mExtTokens[typeIndex][0] != '\'')
typeIndex--;
if (typeIndex <= 0)
return "";
}
if (nodeType == DeclRefExpr) {
while (typeIndex > 0 && std::isalpha(mExtTokens[typeIndex][0]))
typeIndex--;
if (typeIndex <= 0)
return "";
}
if (typeIndex <= 0)
return "";
Comment on lines +430 to +431

@danmar danmar Oct 1, 2026

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This is an AI review. Take it with a grain of salt and feel free to reject it by resolving the comment.

The fix looks correct. I verified that the new crash2 test fails on main (built with -D_GLIBCXX_ASSERTIONS: Assertion '__n < this->size()' failed in getSpelling()) and passes with this PR.

The description says the guard is hoisted, but the two existing if (typeIndex <= 0) return ""; checks in the FunctionDecl/CXXConstructorDecl/CXXMethodDecl and DeclRefExpr branches above are kept. They are now redundant, since this new check covers them. Maybe remove them so there is only one guard? I tried that locally and TestClangImport still passes.

@Nussu06 Nussu06 Oct 2, 2026

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Good point, those two are redundant now. Dropped both so there's just the single guard before the index. TestClangImport still passes.

@danmar danmar Oct 2, 2026

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This is an AI review take it with a grain of salt. Please feel free to reject it by clicking on Resolve button

Thanks, the update looks good to me.

FYI: #8903 also adds a test right after crash() and a TEST_CASE line in the same place in test/testclangimport.cpp, so whichever of the two PRs is merged second will get a trivial merge conflict.

const std::string &str = mExtTokens[typeIndex - 1];
if (startsWith(str,"col:"))
return "";
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8 changes: 8 additions & 0 deletions test/testclangimport.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -139,6 +139,7 @@ class TestClangImport : public TestFixture {
TEST_CASE(valueType2);

TEST_CASE(crash);
TEST_CASE(crash2);
}

std::string parse(const char clang[]) {
Expand Down Expand Up @@ -1372,6 +1373,13 @@ class TestClangImport : public TestFixture {
" `-CompoundStmt 0x5603791b5700 <col:54, col:55>\n";
(void)parse(clang); // don't crash
}

void crash2() {
// getSpelling() indexed mExtTokens[typeIndex - 1] without a lower-bound
// check, so a node whose line carries no ext tokens (typeIndex <= 0) read
// out of bounds.
(void)parse("`-RecordDecl "); // don't crash
}
};

REGISTER_TEST(TestClangImport)