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[libunwind] Don't abort if encoutering invalid .eh_frame_hdr 

Recent Linux kernel release has introduced a bug as part of the ORC
rollout where the vDSO has a valid .eh_frame section, but it's missing
the .eh_frame_hdr section and GNU_EH_FRAME segment has zero size. This
causes libunwind to abort which breaks programs that use libunwind.

The other unwinder implementation (libgcc, non-gnu) instead silently
bail out unless being compiled as debug. This change modifies libunwind
to use the same strategy.

Differential Revision: https://reviews.llvm.org/D57081

llvm-svn: 352016
This commit is contained in:
Petr Hosek 2019-01-24 03:04:42 +00:00
parent 5c0521ac52
commit 8c84e00c71
2 changed files with 14 additions and 8 deletions
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4
libunwind/src/AddressSpace.hpp
View File

@ -535,11 +535,11 @@ inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
#endif
cbdata->sects->dwarf_index_section = eh_frame_hdr_start;
cbdata->sects->dwarf_index_section_length = phdr->p_memsz;
EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
found_hdr = EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
*cbdata->addressSpace, eh_frame_hdr_start, phdr->p_memsz,
hdrInfo);
if (found_hdr)
cbdata->sects->dwarf_section = hdrInfo.eh_frame_ptr;
found_hdr = true;
}
}

16
libunwind/src/EHHeaderParser.hpp
View File

@ -35,7 +35,7 @@ public:
uint8_t table_enc;
};
static void decodeEHHdr(A &addressSpace, pint_t ehHdrStart, pint_t ehHdrEnd,
static bool decodeEHHdr(A &addressSpace, pint_t ehHdrStart, pint_t ehHdrEnd,
EHHeaderInfo &ehHdrInfo);
static bool findFDE(A &addressSpace, pint_t pc, pint_t ehHdrStart,
uint32_t sectionLength,
@ -52,12 +52,14 @@ private:
};
template <typename A>
void EHHeaderParser<A>::decodeEHHdr(A &addressSpace, pint_t ehHdrStart,
bool EHHeaderParser<A>::decodeEHHdr(A &addressSpace, pint_t ehHdrStart,
pint_t ehHdrEnd, EHHeaderInfo &ehHdrInfo) {
pint_t p = ehHdrStart;
uint8_t version = addressSpace.get8(p++);
if (version != 1)
_LIBUNWIND_ABORT("Unsupported .eh_frame_hdr version");
if (version != 1) {
_LIBUNWIND_LOG0("Unsupported .eh_frame_hdr version");
return false;
}
uint8_t eh_frame_ptr_enc = addressSpace.get8(p++);
uint8_t fde_count_enc = addressSpace.get8(p++);
@ -70,6 +72,8 @@ void EHHeaderParser<A>::decodeEHHdr(A &addressSpace, pint_t ehHdrStart,
? 0
: addressSpace.getEncodedP(p, ehHdrEnd, fde_count_enc, ehHdrStart);
ehHdrInfo.table = p;
return true;
}
template <typename A>
@ -101,7 +105,9 @@ bool EHHeaderParser<A>::findFDE(A &addressSpace, pint_t pc, pint_t ehHdrStart,
pint_t ehHdrEnd = ehHdrStart + sectionLength;
EHHeaderParser<A>::EHHeaderInfo hdrInfo;
EHHeaderParser<A>::decodeEHHdr(addressSpace, ehHdrStart, ehHdrEnd, hdrInfo);
if (!EHHeaderParser<A>::decodeEHHdr(addressSpace, ehHdrStart, ehHdrEnd,
hdrInfo))
return false;
size_t tableEntrySize = getTableEntrySize(hdrInfo.table_enc);
pint_t tableEntry;