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ld128 demangle: allow space for 'L' suffix.

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Summary:
Caught by HWASAN on arm64 Android (which uses ld128 for long double). This
was running the existing fuzzer.

The specific minimized fuzz input to reproduce this is:

  __cxa_demangle("1\006ILeeeEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE", 0, 0, 0);

Reviewers: eugenis, srhines, #libc_abi!

Subscribers: kristof.beyls, danielkiss, libcxx-commits

Tags: #libc_abi

Differential Revision: https://reviews.llvm.org/D77924
This commit is contained in:
Elliott Hughes 2020-04-10 17:42:00 -07:00
parent 592b8996bf
commit a7d0b7a786
3 changed files with 19 additions and 2 deletions
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7
libcxxabi/src/demangle/ItaniumDemangle.h
View File

@ -5203,7 +5203,12 @@ struct FloatData<long double>
#else
static const size_t mangled_size = 20; // May need to be adjusted to 16 or 24 on other platforms
#endif
static const size_t max_demangled_size = 40;
// `-0x1.ffffffffffffffffffffffffffffp+16383` + 'L' + '\0' == 42 bytes.
// 28 'f's * 4 bits == 112 bits, which is the number of mantissa bits.
// Negatives are one character longer than positives.
// `0x1.` and `p` are constant, and exponents `+16383` and `-16382` are the
// same length. 1 sign bit, 112 mantissa bits, and 15 exponent bits == 128.
static const size_t max_demangled_size = 42;
static constexpr const char *spec = "%LaL";
};

7
libcxxabi/test/test_demangle.pass.cpp
View File

@ -15,6 +15,8 @@
// Is long double fp80? (Only x87 extended double has 64-bit mantissa)
#define LDBL_FP80 (__LDBL_MANT_DIG__ == 64)
// Is long double fp128?
#define LDBL_FP128 (__LDBL_MANT_DIG__ == 113)
const char* cases[][2] =
{
@ -29837,6 +29839,11 @@ struct FPLiteralCase {
"void test0::h<float>(char (&) [(unsigned int)((sizeof (float)) + (0xap-1L))])",
}},
#endif
#if LDBL_FP128
// This was found by libFuzzer+HWASan on aarch64 Android.
{"1\006ILeeeEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE",
{"\x6<-0x1.cecececececececececececececep+11983"}},
#endif
};
const unsigned NF = sizeof(fp_literal_cases) / sizeof(fp_literal_cases[0]);
const unsigned NEF = sizeof(fp_literal_cases[0].expecting) / sizeof(fp_literal_cases[0].expecting[0]);

7
llvm/include/llvm/Demangle/ItaniumDemangle.h
View File

@ -5203,7 +5203,12 @@ struct FloatData<long double>
#else
static const size_t mangled_size = 20; // May need to be adjusted to 16 or 24 on other platforms
#endif
static const size_t max_demangled_size = 40;
// `-0x1.ffffffffffffffffffffffffffffp+16383` + 'L' + '\0' == 42 bytes.
// 28 'f's * 4 bits == 112 bits, which is the number of mantissa bits.
// Negatives are one character longer than positives.
// `0x1.` and `p` are constant, and exponents `+16383` and `-16382` are the
// same length. 1 sign bit, 112 mantissa bits, and 15 exponent bits == 128.
static const size_t max_demangled_size = 42;
static constexpr const char *spec = "%LaL";
};