Commit 5581990e authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r352016: 

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r352016 | phosek | 2019-01-24 04:04:42 +0100 (Thu, 24 Jan 2019) | 12 lines

[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
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llvm-svn: 353287
parent 35f4f2f7

libunwind/src/AddressSpace.hpp

+3 −3
Original line number Diff line number Diff line
@@ -534,11 +534,11 @@ 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;

          }

        }

libunwind/src/EHHeaderParser.hpp

+11 −5
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ 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,
@@ -53,12 +53,14 @@ 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++);
@@ -71,6 +73,8 @@ 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>
@@ -102,7 +106,9 @@ 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;