Re: [patch 2/3] Fix abort() on missing section headers

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Tue, 25 Feb 2014 23:30:55 +0100, Mark Wielaard wrote:
> We certainly shouldn't abort on bad data!
> But do we even need to continue at this point?
> 
> return result; means we will keep searching through the section table,
> which apparently is busted anyway. So I think it makes sense to cleanup
> and return NULL; instead.
> 
> See how we cleanup and return NULL just below this code when elf_strptr
> fails.

Yes, I agree.


Thanks,
Jan

libdw/
2014-03-02  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix abort() on missing section headers.
	* dwarf_begin_elf.c (check_section): Replace abort call by goto err.
	New label err to return NULL.

Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com>
diff --git a/libdw/dwarf_begin_elf.c b/libdw/dwarf_begin_elf.c
index 6cf3aa1..79daeac 100644
--- a/libdw/dwarf_begin_elf.c
+++ b/libdw/dwarf_begin_elf.c
@@ -187,9 +187,9 @@ check_section (Dwarf *result, GElf_Ehdr *ehdr, Elf_Scn *scn, bool inscngrp)
   /* Get the section header data.  */
   shdr = gelf_getshdr (scn, &shdr_mem);
   if (shdr == NULL)
-    /* This should never happen.  If it does something is
-       wrong in the libelf library.  */
-    abort ();
+    /* We may read /proc/PID/mem with only program headers mapped and section
+       headers out of the mapped pages.  */
+    goto err;
 
   /* Ignore any SHT_NOBITS sections.  Debugging sections should not
      have been stripped, but in case of a corrupt file we won't try
@@ -215,6 +215,7 @@ check_section (Dwarf *result, GElf_Ehdr *ehdr, Elf_Scn *scn, bool inscngrp)
     {
       /* The section name must be valid.  Otherwise is the ELF file
 	 invalid.  */
+    err:
       __libdw_free_zdata (result);
       Dwarf_Sig8_Hash_free (&result->sig8_hash);
       __libdw_seterrno (DWARF_E_INVALID_ELF);