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From: "wilson at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: elfutils-devel@sourceware.org
Subject: [Bug libdw/27805] libdwfl: Unable to extract source line information
 for RISC-V binary
Date: Sat, 01 May 2021 20:48:57 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D27805

Jim Wilson <wilson at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |wilson at gcc dot gnu.org

--- Comment #1 from Jim Wilson <wilson at gcc dot gnu.org> ---
Using readelf -wr to look at the debug_aranges section, I see entries like

  Length:                   44
  Version:                  2
  Offset into .debug_info:  0x987
  Pointer Size:             4
  Segment Size:             0

    Address    Length
    00000000 00000000
    20400132 00000002
    20400134 0000003a
    00000000 00000000

An address/length entry of 0/0 is supposed to mark the end of the list, but
here we have one at the beginning.  This is confusing elfutils which is try=
ing
to move byte by byte through the aranges section. libdw/dwarf_aranges.c has
          /* Two zero values mark the end.  */
          if (range_address =3D=3D 0 && range_length =3D=3D 0)
            break;
and then assumes that the next entry is immediately following, which it isn=
't,
and it ends up reading garbage.  binutils seems to be using the length fiel=
d to
find the last entry.  And readelf is ignoring the 0/0 end of list rule so t=
hat
we can see the invalid entries.

There are a lot of aranges that have 0/0 entries not at the end of the list.

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