Re: [Libunwind-devel] [PATCH] Check that the CIE is within the segment

[Peter Wu]

On Thursday 04 December 2014 14:00:53 Arun Sharma wrote:
> The logic looks good to me. Could you resend the patch replacing tabs
> with spaces?

The context did not have tabs, so I followed that and used spaces too.
Where do you see tabs? Are you referring to the number of spaces?

> On Wed, Nov 26, 2014 at 2:40 AM, Peter Wu <address@hidden> wrote:
> > 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 <address@hidden>
> [...]
> >
> > diff --git a/src/dwarf/Gfind_proc_info-lsb.c 
> > b/src/dwarf/Gfind_proc_info-lsb.c
> > index e1bfbe7..32f165a 100644
> > --- a/src/dwarf/Gfind_proc_info-lsb.c
> > +++ b/src/dwarf/Gfind_proc_info-lsb.c
> [..]
> > @@ -902,6 +904,8 @@ dwarf_search_unwind_table (unw_addr_space_t as, 
> > unw_word_t ip,
> >              "fde_addr = %lx\n", (long) e->fde_offset, (long) segbase,
> >              (long) debug_frame_base, (long) fde_addr);
> >    if ((ret = dwarf_extract_proc_info_from_fde (as, a, &fde_addr, pi,
> > +                                               debug_frame_base ?
> > +                                               debug_frame_base : segbase,
> >                                                 need_unwind_info,
> >                                                 debug_frame_base, arg)) < 0)
> >      return ret;
> 
> May be cleaner to use debug_frame_base != 0 to indicate that it's a boolean.

Sure, should I send a new patch or will you fix it up locally?
-- 
Kind regards,
Peter
https://lekensteyn.nl