Due to a bug in the gold linker[1], the .eh_frame and .eh_frame_hdr
sections contains garbage. When dwarf_extract_proc_info_from_fde tried
to look up the begin of the CIE subsection, it would underflow the
.eh_frame segment, resulting in a crash[2].
This patch avoids that crash by checking whether the CIE pointer is
located after the begin of the .eh_frame section. The variable "base"
was misused in various places as a boolean (decode as .debug_frame or
decode as .eh_frame). These instances have been renamed to
is_debug_frame where applicable.
Tested on Linux x86_64.
[1]: https://sourceware.org/bugzilla/show_bug.cgi?id=17639
[2]: http://lists.nongnu.org/archive/html/libunwind-devel/2014-11/msg00009.html
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
(parse_cie): Adjust for moving DWARF2 extra-info from
unw_dyn_dwarf_fde_info_t to dwarf_cie_info.
Add support for `S' augmentation ("special frames").
(dwarf_extract_proc_info_from_fde): Rename frm dwarf_parse_fde().
Convert to returning data via dwarf_cie_info rather than
unw_dyn-dwarf_fde_info_t. Allow 0-length FDE since those
can be used to indicate the end of the FDE-table. Return
the end of the FDE via *ADDRP. Ignore CIEs (we may pick them
up during linear searches through the FDE-table).
Fill in the unwind-info only if really needed. When needed,
return the info via a dynamically allocated dwarf_cie_info
structure. Add support for `S' augmentation (ABI/tag pairs).
(Logical change 1.290)
