x86: Check for valid PLT section size

Update x86 get_synthetic_symtab to check for valid PLT section size
before examining PLT section contents.

	PR binutils/22018
	* elf32-i386.c (elf_i386_get_synthetic_symtab): Check for valid
	PLT section size.
	* elf64-x86-64.c (elf_x86_64_get_synthetic_symtab): Likewise.

3 files changed, 31 insertions, 9 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 063253f..419c311 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2017-08-28  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR binutils/22018
+	* elf32-i386.c (elf_i386_get_synthetic_symtab): Check for valid
+	PLT section size.
+	* elf64-x86-64.c (elf_x86_64_get_synthetic_symtab): Likewise.
+
 2017-08-27  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* elf32-i386.c (elf_i386_link_hash_newfunc): Initialize
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index 999cd48..05ba2c3 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -6362,7 +6362,7 @@ elf_i386_get_synthetic_symtab (bfd *abfd,
   for (j = 0; plts[j].name != NULL; j++)
     {
       plt = bfd_get_section_by_name (abfd, plts[j].name);
-      if (plt == NULL)
+      if (plt == NULL || plt->size == 0)
 	continue;
 
       /* Get the PLT section contents.  */
@@ -6378,7 +6378,9 @@ elf_i386_get_synthetic_symtab (bfd *abfd,
 
       /* Check what kind of PLT it is.  */
       plt_type = plt_unknown;
-      if (plts[j].type == plt_unknown)
+      if (plts[j].type == plt_unknown
+	  && (plt->size >= (lazy_plt->plt0_entry_size
+			    + lazy_plt->plt_entry_size)))
 	{
 	  /* Match lazy PLT first.  */
 	  if (memcmp (plt_contents, lazy_plt->plt0_entry,
@@ -6387,7 +6389,7 @@ elf_i386_get_synthetic_symtab (bfd *abfd,
 	      /* The fist entry in the lazy IBT PLT is the same as the
 		 normal lazy PLT.  */
 	      if (lazy_ibt_plt != NULL
-		  && (memcmp (plt_contents + lazy_ibt_plt->plt_entry_size,
+		  && (memcmp (plt_contents + lazy_ibt_plt->plt0_entry_size,
 			      lazy_ibt_plt->plt_entry,
 			      lazy_ibt_plt->plt_got_offset) == 0))
 		plt_type = plt_lazy | plt_second;
@@ -6400,7 +6402,7 @@ elf_i386_get_synthetic_symtab (bfd *abfd,
 	      /* The fist entry in the PIC lazy IBT PLT is the same as
 		 the normal PIC lazy PLT.  */
 	      if (lazy_ibt_plt != NULL
-		  && (memcmp (plt_contents + lazy_ibt_plt->plt_entry_size,
+		  && (memcmp (plt_contents + lazy_ibt_plt->plt0_entry_size,
 			      lazy_ibt_plt->pic_plt_entry,
 			      lazy_ibt_plt->plt_got_offset) == 0))
 		plt_type = plt_lazy | plt_pic | plt_second;
@@ -6410,7 +6412,8 @@ elf_i386_get_synthetic_symtab (bfd *abfd,
 	}
 
       if (non_lazy_plt != NULL
-	  && (plt_type == plt_unknown || plt_type == plt_non_lazy))
+	  && (plt_type == plt_unknown || plt_type == plt_non_lazy)
+	  && plt->size >= non_lazy_plt->plt_entry_size)
 	{
 	  /* Match non-lazy PLT.  */
 	  if (memcmp (plt_contents, non_lazy_plt->plt_entry,
@@ -6422,7 +6425,8 @@ elf_i386_get_synthetic_symtab (bfd *abfd,
 	}
 
       if ((non_lazy_ibt_plt != NULL)
-	  && (plt_type == plt_unknown || plt_type == plt_second))
+	  && (plt_type == plt_unknown || plt_type == plt_second)
+	  && plt->size >= non_lazy_ibt_plt->plt_entry_size)
 	{
 	  if (memcmp (plt_contents,
 		      non_lazy_ibt_plt->plt_entry,
@@ -6480,6 +6484,9 @@ elf_i386_get_synthetic_symtab (bfd *abfd,
 	got_addr = (bfd_vma) -1;
     }
 
+  if (count == 0)
+    return -1;
+
   size = count * sizeof (asymbol);
 
   /* Allocate space for @plt suffixes.  */
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index c9c6dba..25ce295 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -6763,7 +6763,7 @@ elf_x86_64_get_synthetic_symtab (bfd *abfd,
   for (j = 0; plts[j].name != NULL; j++)
     {
       plt = bfd_get_section_by_name (abfd, plts[j].name);
-      if (plt == NULL)
+      if (plt == NULL || plt->size == 0)
 	continue;
 
       /* Get the PLT section contents.  */
@@ -6779,7 +6779,9 @@ elf_x86_64_get_synthetic_symtab (bfd *abfd,
 
       /* Check what kind of PLT it is.  */
       plt_type = plt_unknown;
-      if (plts[j].type == plt_unknown)
+      if (plts[j].type == plt_unknown
+	  && (plt->size >= (lazy_plt->plt_entry_size
+			    + lazy_plt->plt_entry_size)))
 	{
 	  /* Match lazy PLT first.  Need to check the first two
 	     instructions.   */
@@ -6807,7 +6809,8 @@ elf_x86_64_get_synthetic_symtab (bfd *abfd,
 	}
 
       if (non_lazy_plt != NULL
-	  && (plt_type == plt_unknown || plt_type == plt_non_lazy))
+	  && (plt_type == plt_unknown || plt_type == plt_non_lazy)
+	  && plt->size >= non_lazy_plt->plt_entry_size)
 	{
 	  /* Match non-lazy PLT.  */
 	  if (memcmp (plt_contents, non_lazy_plt->plt_entry,
@@ -6818,6 +6821,7 @@ elf_x86_64_get_synthetic_symtab (bfd *abfd,
       if (plt_type == plt_unknown || plt_type == plt_second)
 	{
 	  if (non_lazy_bnd_plt != NULL
+	      && plt->size >= non_lazy_bnd_plt->plt_entry_size
 	      && (memcmp (plt_contents, non_lazy_bnd_plt->plt_entry,
 			  non_lazy_bnd_plt->plt_got_offset) == 0))
 	    {
@@ -6826,6 +6830,7 @@ elf_x86_64_get_synthetic_symtab (bfd *abfd,
 	      non_lazy_plt = non_lazy_bnd_plt;
 	    }
 	  else if (non_lazy_ibt_plt != NULL
+		   && plt->size >= non_lazy_ibt_plt->plt_entry_size
 		   && (memcmp (plt_contents,
 			       non_lazy_ibt_plt->plt_entry,
 			       non_lazy_ibt_plt->plt_got_offset) == 0))
@@ -6871,6 +6876,9 @@ elf_x86_64_get_synthetic_symtab (bfd *abfd,
       plts[j].contents = plt_contents;
     }
 
+  if (count == 0)
+    return -1;
+
   size = count * sizeof (asymbol);
 
   /* Allocate space for @plt suffixes.  */