[patch] binutils-2.28-bfd-elf.c-fix-out-of-bounds-access-in-find_link.patch

binutils-2.28-bfd-elf.c-fix-out-of-bounds-access-in-find_link.patch (text/plain), 1.95 KB, created by Sergei Trofimovich (RETIRED) on 2017-06-23 21:34:59 UTC

From 45ad6ab2d45a7cda9b8f81f4426370eb9f78e221 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <[e-mail]>
Date: Fri, 23 Jun 2017 22:09:29 +0100
Subject: [PATCH] bfd/elf.c: fix out-of-bounds access in find_link()

The out-of-bounds access is reproducible on 'ia64-strip' command
(see sample from https://bugs.gentoo.org/show_bug.cgi?id=622500)

The output file contains less section than original one.
This tricks 'hint' access to go out-of-bounds:

==17093==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61a000000598 ...
READ of size 8 at 0x61a000000598 thread T0
    #0 0x7feeb6dd4333 in find_link binutils-gdb/bfd/elf.c:1295
    #1 0x7feeb6dd48a1 in copy_special_section_fields binutils-gdb/bfd/elf.c:1379
    #2 0x7feeb6dd5391 in _bfd_elf_copy_private_bfd_data binutils-gdb/bfd/elf.c:1501
    #3 0x5623789a0952 in copy_object binutils-gdb/binutils/objcopy.c:2974
    #4 0x5623789a25d4 in copy_file binutils-gdb/binutils/objcopy.c:3336
    #5 0x5623789a6856 in strip_main binutils-gdb/binutils/objcopy.c:4261
    #6 0x5623789ab0f9 in main binutils-gdb/binutils/objcopy.c:5368
    #7 0x7feeb650f3f9 in __libc_start_main (/lib64/libc.so.6+0x39648203f9)
    #8 0x562378996259 in _start (binutils-gdb/binutils/.libs/strip-new+0x16259)

The fix is simple: check hint against array size.
This makes gcc compile successfully on ia64.

Bug: https://bugs.gentoo.org/622500
Signed-off-by: Sergei Trofimovich <[e-mail]>
---
 bfd/elf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/bfd/elf.c b/bfd/elf.c
index 5f37e7f79c..abb1499893 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -1291,7 +1291,8 @@ find_link (const bfd * obfd, const Elf_Internal_Shdr * iheader, const unsigned i
   BFD_ASSERT (iheader != NULL);
 
   /* See PR 20922 for a reproducer of the NULL test.  */
-  if (oheaders[hint] != NULL
+  if (hint < elf_numsections (obfd)
+      && oheaders[hint] != NULL
       && section_match (oheaders[hint], iheader))
     return hint;
 
-- 
2.13.1