From: H.J. Lu <hjl.tools@gmail.com>
Date: Sat, 22 Nov 2014 16:58:07 +0000 (-0800)
Subject: Check branch displacement overflow in x86-64 PLT entry
X-Git-Tag: gdb-7.9.0-release~538
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=35a14c6b54b63adc6b6ef28a4e4403bb271b9bdd;p=external%2Fbinutils.git

Check branch displacement overflow in x86-64 PLT entry

Displacement of branch to PLT0 in x86-64 PLT entry is signed 32-bit.
This patch adds a sanity check.  We will only see the failure when PLT
size is > 2GB.

	* elf64-x86-64.c (elf_x86_64_finish_dynamic_symbol): Check
	branch displacement overflow in PLT entry.
---

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 5700c51..040576a 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,8 @@
+2014-11-22  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* elf64-x86-64.c (elf_x86_64_finish_dynamic_symbol): Check
+	branch displacement overflow in PLT entry.
+
 2014-11-21  Nick Clifton  <nickc@redhat.com>
 
 	PR binutils/17512
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index c64ff4f..8859429 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -4906,11 +4906,19 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
       /* Don't fill PLT entry for static executables.  */
       if (plt == htab->elf.splt)
 	{
+	  bfd_vma plt0_offset = h->plt.offset + plt_plt_insn_end;
+
 	  /* Put relocation index.  */
 	  bfd_put_32 (output_bfd, plt_index,
 		      plt->contents + h->plt.offset + abed->plt_reloc_offset);
-	  /* Put offset for jmp .PLT0.  */
-	  bfd_put_32 (output_bfd, - (h->plt.offset + plt_plt_insn_end),
+
+	  /* Put offset for jmp .PLT0 and check for overflow.  We don't
+	     check relocation index for overflow since branch displacement
+	     will overflow first.  */
+	  if (plt0_offset > 0x80000000)
+	    info->callbacks->einfo (_("%F%B: branch displacement overflow in PLT entry for `%s'\n"),
+				    output_bfd, h->root.root.string);
+	  bfd_put_32 (output_bfd, - plt0_offset,
 		      plt->contents + h->plt.offset + plt_plt_offset);
 	}