Re: asan: readelf: process_mips_specific buffer overflow

Let's do without that unnecessary internal option buffer.  This also
fixes another bug in that the REGINFO data was being taken from the
calloc'd internal option buffer, so was all zeros.

	* readelf.c (process_mips_specific): Don't alloc memory for
	Elf_Internal_Options.

2 files changed, 54 insertions, 62 deletions

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index 25e21ff6dca..30eae9709d4 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,5 +1,10 @@
 2020-06-11  Alan Modra  <amodra@gmail.com>
 
+	* readelf.c (process_mips_specific): Don't alloc memory for
+	Elf_Internal_Options.
+
+2020-06-11  Alan Modra  <amodra@gmail.com>
+
 	* readelf.c (process_mips_specific): Assert size of internal
 	types match size of external types, and simplify allocation of
 	internal buffer.  Catch possible integer overflow when sanity
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 0705a49c0d8..101fd66ccb7 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -16894,47 +16894,28 @@ process_mips_specific (Filedata * filedata)
                                                 sect->sh_size, _("options"));
       if (eopt)
 	{
-	  Elf_Internal_Options * iopt;
-	  Elf_Internal_Options * option;
-
-	  assert (sizeof (Elf_Internal_Options) == sizeof (Elf_External_Options));
-	  assert (sizeof (Elf32_RegInfo) == sizeof (Elf32_External_RegInfo));
-	  assert (sizeof (Elf64_Internal_RegInfo) == sizeof (Elf64_External_RegInfo));
-	  iopt = (Elf_Internal_Options *) cmalloc (sect->sh_size, 1);
-	  if (iopt == NULL)
-	    {
-	      error (_("Out of memory allocating space for MIPS options\n"));
-	      free (eopt);
-	      return FALSE;
-	    }
+	  Elf_Internal_Options option;
 
 	  offset = cnt = 0;
-	  option = iopt;
-	  
 	  while (offset <= sect->sh_size - sizeof (* eopt))
 	    {
 	      Elf_External_Options * eoption;
+	      unsigned int optsize;
 
 	      eoption = (Elf_External_Options *) ((char *) eopt + offset);
 
-	      option->kind = BYTE_GET (eoption->kind);
-	      option->size = BYTE_GET (eoption->size);
-	      option->section = BYTE_GET (eoption->section);
-	      option->info = BYTE_GET (eoption->info);
+	      optsize = BYTE_GET (eoption->size);
 
 	      /* PR 17531: file: ffa0fa3b.  */
-	      if (option->size < sizeof (* eopt)
-		  || option->size > sect->sh_size - offset)
+	      if (optsize < sizeof (* eopt)
+		  || optsize > sect->sh_size - offset)
 		{
 		  error (_("Invalid size (%u) for MIPS option\n"),
-			 option->size);
-		  free (iopt);
+			 optsize);
 		  free (eopt);
 		  return FALSE;
 		}
-	      offset += option->size;
-
-	      ++option;
+	      offset += optsize;
 	      ++cnt;
 	    }
 
@@ -16947,14 +16928,21 @@ process_mips_specific (Filedata * filedata)
 	  while (cnt-- > 0)
 	    {
 	      size_t len;
+	      Elf_External_Options * eoption;
+
+	      eoption = (Elf_External_Options *) ((char *) eopt + offset);
+
+	      option.kind = BYTE_GET (eoption->kind);
+	      option.size = BYTE_GET (eoption->size);
+	      option.section = BYTE_GET (eoption->section);
+	      option.info = BYTE_GET (eoption->info);
 
-	      option = (Elf_Internal_Options *) ((char *) iopt + offset);
-	      switch (option->kind)
+	      switch (option.kind)
 		{
 		case ODK_NULL:
 		  /* This shouldn't happen.  */
 		  printf (" NULL       %" PRId16 " %" PRIx32,
-			  option->section, option->info);
+			  option.section, option.info);
 		  break;
 
 		case ODK_REGINFO:
@@ -16965,8 +16953,8 @@ process_mips_specific (Filedata * filedata)
 		      Elf32_RegInfo reginfo;
 
 		      /* 32bit form.  */
-		      if (option->size < (sizeof (Elf_External_Options)
-					  + sizeof (Elf32_External_RegInfo)))
+		      if (option.size < (sizeof (Elf_External_Options)
+					 + sizeof (Elf32_External_RegInfo)))
 			{
 			  printf (_("<corrupt>\n"));
 			  error (_("Truncated MIPS REGINFO option\n"));
@@ -16974,7 +16962,7 @@ process_mips_specific (Filedata * filedata)
 			  break;
 			}
 
-		      ereg = (Elf32_External_RegInfo *) (option + 1);
+		      ereg = (Elf32_External_RegInfo *) (eoption + 1);
 
 		      reginfo.ri_gprmask = BYTE_GET (ereg->ri_gprmask);
 		      reginfo.ri_cprmask[0] = BYTE_GET (ereg->ri_cprmask[0]);
@@ -16997,8 +16985,8 @@ process_mips_specific (Filedata * filedata)
 		      Elf64_External_RegInfo * ereg;
 		      Elf64_Internal_RegInfo reginfo;
 
-		      if (option->size < (sizeof (Elf_External_Options)
-					  + sizeof (Elf64_External_RegInfo)))
+		      if (option.size < (sizeof (Elf_External_Options)
+					 + sizeof (Elf64_External_RegInfo)))
 			{
 			  printf (_("<corrupt>\n"));
 			  error (_("Truncated MIPS REGINFO option\n"));
@@ -17006,7 +16994,7 @@ process_mips_specific (Filedata * filedata)
 			  break;
 			}
 
-		      ereg = (Elf64_External_RegInfo *) (option + 1);
+		      ereg = (Elf64_External_RegInfo *) (eoption + 1);
 		      reginfo.ri_gprmask    = BYTE_GET (ereg->ri_gprmask);
 		      reginfo.ri_cprmask[0] = BYTE_GET (ereg->ri_cprmask[0]);
 		      reginfo.ri_cprmask[1] = BYTE_GET (ereg->ri_cprmask[1]);
@@ -17022,45 +17010,45 @@ process_mips_specific (Filedata * filedata)
 			      reginfo.ri_cprmask[0], reginfo.ri_cprmask[1],
 			      reginfo.ri_cprmask[2], reginfo.ri_cprmask[3]);
 		    }
-		  offset += option->size;
+		  offset += option.size;
 		  continue;
 
 		case ODK_EXCEPTIONS:
 		  fputs (" EXCEPTIONS fpe_min(", stdout);
-		  process_mips_fpe_exception (option->info & OEX_FPU_MIN);
+		  process_mips_fpe_exception (option.info & OEX_FPU_MIN);
 		  fputs (") fpe_max(", stdout);
-		  process_mips_fpe_exception ((option->info & OEX_FPU_MAX) >> 8);
+		  process_mips_fpe_exception ((option.info & OEX_FPU_MAX) >> 8);
 		  fputs (")", stdout);
 
-		  if (option->info & OEX_PAGE0)
+		  if (option.info & OEX_PAGE0)
 		    fputs (" PAGE0", stdout);
-		  if (option->info & OEX_SMM)
+		  if (option.info & OEX_SMM)
 		    fputs (" SMM", stdout);
-		  if (option->info & OEX_FPDBUG)
+		  if (option.info & OEX_FPDBUG)
 		    fputs (" FPDBUG", stdout);
-		  if (option->info & OEX_DISMISS)
+		  if (option.info & OEX_DISMISS)
 		    fputs (" DISMISS", stdout);
 		  break;
 
 		case ODK_PAD:
 		  fputs (" PAD       ", stdout);
-		  if (option->info & OPAD_PREFIX)
+		  if (option.info & OPAD_PREFIX)
 		    fputs (" PREFIX", stdout);
-		  if (option->info & OPAD_POSTFIX)
+		  if (option.info & OPAD_POSTFIX)
 		    fputs (" POSTFIX", stdout);
-		  if (option->info & OPAD_SYMBOL)
+		  if (option.info & OPAD_SYMBOL)
 		    fputs (" SYMBOL", stdout);
 		  break;
 
 		case ODK_HWPATCH:
 		  fputs (" HWPATCH   ", stdout);
-		  if (option->info & OHW_R4KEOP)
+		  if (option.info & OHW_R4KEOP)
 		    fputs (" R4KEOP", stdout);
-		  if (option->info & OHW_R8KPFETCH)
+		  if (option.info & OHW_R8KPFETCH)
 		    fputs (" R8KPFETCH", stdout);
-		  if (option->info & OHW_R5KEOP)
+		  if (option.info & OHW_R5KEOP)
 		    fputs (" R5KEOP", stdout);
-		  if (option->info & OHW_R5KCVTL)
+		  if (option.info & OHW_R5KCVTL)
 		    fputs (" R5KCVTL", stdout);
 		  break;
 
@@ -17076,43 +17064,43 @@ process_mips_specific (Filedata * filedata)
 
 		case ODK_HWAND:
 		  fputs (" HWAND     ", stdout);
-		  if (option->info & OHWA0_R4KEOP_CHECKED)
+		  if (option.info & OHWA0_R4KEOP_CHECKED)
 		    fputs (" R4KEOP_CHECKED", stdout);
-		  if (option->info & OHWA0_R4KEOP_CLEAN)
+		  if (option.info & OHWA0_R4KEOP_CLEAN)
 		    fputs (" R4KEOP_CLEAN", stdout);
 		  break;
 
 		case ODK_HWOR:
 		  fputs (" HWOR      ", stdout);
-		  if (option->info & OHWA0_R4KEOP_CHECKED)
+		  if (option.info & OHWA0_R4KEOP_CHECKED)
 		    fputs (" R4KEOP_CHECKED", stdout);
-		  if (option->info & OHWA0_R4KEOP_CLEAN)
+		  if (option.info & OHWA0_R4KEOP_CLEAN)
 		    fputs (" R4KEOP_CLEAN", stdout);
 		  break;
 
 		case ODK_GP_GROUP:
 		  printf (" GP_GROUP  %#06x  self-contained %#06x",
-			  option->info & OGP_GROUP,
-			  (option->info & OGP_SELF) >> 16);
+			  option.info & OGP_GROUP,
+			  (option.info & OGP_SELF) >> 16);
 		  break;
 
 		case ODK_IDENT:
 		  printf (" IDENT     %#06x  self-contained %#06x",
-			  option->info & OGP_GROUP,
-			  (option->info & OGP_SELF) >> 16);
+			  option.info & OGP_GROUP,
+			  (option.info & OGP_SELF) >> 16);
 		  break;
 
 		default:
 		  /* This shouldn't happen.  */
 		  printf (" %3d ???     %" PRId16 " %" PRIx32,
-			  option->kind, option->section, option->info);
+			  option.kind, option.section, option.info);
 		  break;
 		}
 
 	      len = sizeof (* eopt);
-	      while (len < option->size)
+	      while (len < option.size)
 		{
-		  unsigned char datum = * ((unsigned char *) eopt + offset + len);
+		  unsigned char datum = *((unsigned char *) eoption + len);
 
 		  if (ISPRINT (datum))
 		    printf ("%c", datum);
@@ -17122,9 +17110,8 @@ process_mips_specific (Filedata * filedata)
 		}
 	      fputs ("\n", stdout);
 
-	      offset += option->size;
+	      offset += option.size;
 	    }
-	  free (iopt);
 	  free (eopt);
 	}
       else