[binutils-gdb] objcopy section alignment

[binutils-gdb] objcopy section alignment

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=578a7392c33c7c7cde5559278e519c75047318c9

commit 578a7392c33c7c7cde5559278e519c75047318c9
Author: Alan Modra <amodra@gmail.com>
Date:   Sat Aug 6 14:57:27 2022 +0930

    objcopy section alignment
    
    bfd_set_section_alignment currently always returns true.  This patch
    changes it to return false on silly alignment values, avoiding yet
    another way to trigger ubsan errors like coffcode.h:3192:12: runtime
    error: shift exponent 299 is too large for 32-bit type 'int'.  We'll
    catch that one in objcopy.c:setup_sections.  However, setup_sections
    gives up on other setup operations that are necessary even after an
    error of some sort.  Change that to keep going, which might change the
    error message but that shouldn't matter in the least.
    
    bfd/
            * section.c (bfd_set_section_alignment): Return false and
            don't set alignment_power for stupidly large alignments.
            * bfd-in2.h: Regenerate.
            * coffcode.h (coff_compute_section_file_positions): Don't use
            an int constant when calculating alignment.
    binutils/
            * objcopy.c (setup_section): Keep on going after hitting
            non-fatal errors.

Diff:
---
 bfd/bfd-in2.h      |  2 ++
 bfd/coffcode.h     |  9 +++++----
 bfd/section.c      |  2 ++
 binutils/objcopy.c | 26 +++++++-------------------
 4 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 0d2e915b413..4ab7e2d6934 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -1201,6 +1201,8 @@ bfd_set_section_lma (asection *sec, bfd_vma val)
 static inline bool
 bfd_set_section_alignment (asection *sec, unsigned int val)
 {
+  if (val >= sizeof (bfd_vma) * 8 - 1)
+    return false;
   sec->alignment_power = val;
   return true;
 }
diff --git a/bfd/coffcode.h b/bfd/coffcode.h
index 0dc68a9a25f..798b9f249b5 100644
--- a/bfd/coffcode.h
+++ b/bfd/coffcode.h
@@ -3189,7 +3189,7 @@ coff_compute_section_file_positions (bfd * abfd)
 #ifdef COFF_IMAGE_WITH_PE
 	  sofar = BFD_ALIGN (sofar, page_size);
 #else
-	  sofar = BFD_ALIGN (sofar, 1 << current->alignment_power);
+	  sofar = BFD_ALIGN (sofar, (bfd_vma) 1 << current->alignment_power);
 #endif
 
 #ifdef RS6000COFF_C
@@ -3259,7 +3259,7 @@ coff_compute_section_file_positions (bfd * abfd)
 
 	  old_size = current->size;
 	  current->size = BFD_ALIGN (current->size,
-				     1 << current->alignment_power);
+				     (bfd_vma) 1 << current->alignment_power);
 	  align_adjust = current->size != old_size;
 	  sofar += current->size - old_size;
 	}
@@ -3269,7 +3269,7 @@ coff_compute_section_file_positions (bfd * abfd)
 #ifdef COFF_IMAGE_WITH_PE
 	  sofar = BFD_ALIGN (sofar, page_size);
 #else
-	  sofar = BFD_ALIGN (sofar, 1 << current->alignment_power);
+	  sofar = BFD_ALIGN (sofar, (bfd_vma) 1 << current->alignment_power);
 #endif
 	  align_adjust = sofar != old_sofar;
 	  current->size += sofar - old_sofar;
@@ -3315,7 +3315,8 @@ coff_compute_section_file_positions (bfd * abfd)
   /* Make sure the relocations are aligned.  We don't need to make
      sure that this byte exists, because it will only matter if there
      really are relocs.  */
-  sofar = BFD_ALIGN (sofar, 1 << COFF_DEFAULT_SECTION_ALIGNMENT_POWER);
+  sofar = BFD_ALIGN (sofar,
+		     (bfd_vma) 1 << COFF_DEFAULT_SECTION_ALIGNMENT_POWER);
 
   obj_relocbase (abfd) = sofar;
   abfd->output_has_begun = true;
diff --git a/bfd/section.c b/bfd/section.c
index 5a487ce6c6f..c7a02d729f2 100644
--- a/bfd/section.c
+++ b/bfd/section.c
@@ -631,6 +631,8 @@ CODE_FRAGMENT
 .static inline bool
 .bfd_set_section_alignment (asection *sec, unsigned int val)
 .{
+.  if (val >= sizeof (bfd_vma) * 8 - 1)
+.    return false;
 .  sec->alignment_power = val;
 .  return true;
 .}
diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index 21c3a7127c8..b907b02d5e7 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -4014,7 +4014,7 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
   bfd_vma vma;
   bfd_vma lma;
   flagword flags;
-  const char *err;
+  const char *err = NULL;
   const char * name;
   const char * new_name;
   char *prefix = NULL;
@@ -4097,10 +4097,7 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
   else if (extract_symbol)
     size = 0;
   if (!bfd_set_section_size (osection, size))
-    {
-      err = _("failed to set size");
-      goto loser;
-    }
+    err = _("failed to set size");
 
   vma = bfd_section_vma (isection);
   p = find_section_list (bfd_section_name (isection), false,
@@ -4116,10 +4113,7 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
     vma += change_section_address;
 
   if (!bfd_set_section_vma (osection, vma))
-    {
-      err = _("failed to set vma");
-      goto loser;
-    }
+    err = _("failed to set vma");
 
   lma = isection->lma;
   p = find_section_list (bfd_section_name (isection), false,
@@ -4146,10 +4140,7 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
   /* FIXME: This is probably not enough.  If we change the LMA we
      may have to recompute the header for the file as well.  */
   if (!bfd_set_section_alignment (osection, alignment))
-    {
-      err = _("failed to set alignment");
-      goto loser;
-    }
+    err = _("failed to set alignment");
 
   /* Copy merge entity size.  */
   osection->entsize = isection->entsize;
@@ -4178,16 +4169,13 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
   /* Allow the BFD backend to copy any private data it understands
      from the input section to the output section.  */
   if (!bfd_copy_private_section_data (ibfd, isection, obfd, osection))
-    {
-      err = _("failed to copy private data");
-      goto loser;
-    }
+    err = _("failed to copy private data");
 
   if (make_nobits)
     elf_section_type (osection) = SHT_NOBITS;
 
-  /* All went well.  */
-  return;
+  if (!err)
+    return;
 
  loser:
   status = 1;