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[clang][lex] Speculative fix for buffer overrun on raw string parse 

This attempts to fix a (non-deterministic) buffer overrun when parsing raw string literals during modular build.

Similar fix to 4e5b5c36f4.

Reviewed By: beccadax

Differential Revision: https://reviews.llvm.org/D94950
This commit is contained in:
Jan Svoboda 2021-03-15 15:07:53 +01:00
parent e582c073d1
commit 23cc8ebf59
1 changed files with 14 additions and 2 deletions
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16
clang/lib/Lex/LiteralSupport.cpp
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@ -1628,16 +1628,28 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks){
// Check for raw string
if (ThisTokBuf[0] == 'R') {
if (ThisTokBuf[1] != '"') {
// The file may have come from PCH and then changed after loading the
// PCH; Fail gracefully.
return DiagnoseLexingError(StringToks[i].getLocation());
}
ThisTokBuf += 2; // skip R"
// C++11 [lex.string]p2: A `d-char-sequence` shall consist of at most 16
// characters.
constexpr unsigned MaxRawStrDelimLen = 16;
const char *Prefix = ThisTokBuf;
while (ThisTokBuf[0] != '(')
while (ThisTokBuf - Prefix < MaxRawStrDelimLen && ThisTokBuf[0] != '(')
++ThisTokBuf;
if (ThisTokBuf[0] != '(')
return DiagnoseLexingError(StringToks[i].getLocation());
++ThisTokBuf; // skip '('
// Remove same number of characters from the end
ThisTokEnd -= ThisTokBuf - Prefix;
assert(ThisTokEnd >= ThisTokBuf && "malformed raw string literal");
if (ThisTokEnd < ThisTokBuf)
return DiagnoseLexingError(StringToks[i].getLocation());
// C++14 [lex.string]p4: A source-file new-line in a raw string literal
// results in a new-line in the resulting execution string-literal.