[COMMITTED] libelf: elf_getshdrstrndx cannot use SHN_XINDEX without section headers.

[Mark Wielaard]

Signed-off-by: Mark Wielaard <m...@redhat.com>
---
 libelf/ChangeLog           |  5 +++++
 libelf/elf_getshdrstrndx.c | 15 +++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index ef5da43..633a892 100644
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,5 +1,10 @@
 2014-11-16  Mark Wielaard  <m...@redhat.com>
 
+       * elf_getshdrstrndx.c: Check there are section headers before
+       handling SHN_XINDEX.
+
+2014-11-16  Mark Wielaard  <m...@redhat.com>
+
        * elf32_getphdr.c (getphdr_wrlock): Check e_phoff isn't zero.
        Check for too many pheaders.
        * elf_getphdrnum.c (__elf_getphdrnum_rdlock): Check section zero
diff --git a/libelf/elf_getshdrstrndx.c b/libelf/elf_getshdrstrndx.c
index 1dbed4c..6f8d66e 100644
--- a/libelf/elf_getshdrstrndx.c
+++ b/libelf/elf_getshdrstrndx.c
@@ -92,6 +92,13 @@ elf_getshdrstrndx (elf, dst)
          if (elf->class == ELFCLASS32)
            {
              size_t offset;
+             if (unlikely (elf->state.elf32.scns.cnt == 0))
+               {
+                 /* Cannot use SHN_XINDEX without section headers.  */
+                 __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
+                 result = -1;
+                 goto out;
+               }
 
              if (elf->state.elf32.scns.data[0].shdr.e32 != NULL)
                {
@@ -146,6 +153,14 @@ elf_getshdrstrndx (elf, dst)
            }
          else
            {
+             if (unlikely (elf->state.elf64.scns.cnt == 0))
+               {
+                 /* Cannot use SHN_XINDEX without section headers.  */
+                 __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
+                 result = -1;
+                 goto out;
+               }
+
              if (elf->state.elf64.scns.data[0].shdr.e64 != NULL)
                {
                  num = elf->state.elf64.scns.data[0].shdr.e64->sh_link;
-- 
1.8.3.1