[binutils-gdb] PR26435, PR26436 UBSAN: elf32-cr16.c:928 left shift

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=34d8e6d0c5f3c51d0e7858572791d8269b9d0f1c

commit 34d8e6d0c5f3c51d0e7858572791d8269b9d0f1c
Author: Alan Modra <amodra@gmail.com>
Date:   Sun Aug 30 19:37:15 2020 +0930

    PR26435, PR26436 UBSAN: elf32-cr16.c:928 left shift
    
            PR 26435
            PR 26436
            * elf32-cr16.c (cr16_elf_final_link_relocate): Calculate reloc_bits
            without undefined behaviour.

Diff:
---
 bfd/ChangeLog    | 7 +++++++
 bfd/elf32-cr16.c | 5 +----
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index f3d204e1dc7..31c74bf8bee 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2020-08-30  Alan Modra  <amodra@gmail.com>
+
+	PR 26435
+	PR 26436
+	* elf32-cr16.c (cr16_elf_final_link_relocate): Calculate reloc_bits
+	without undefined behaviour.
+
 2020-08-29  Nick Clifton  <nickc@redhat.com>
 
 	PR 26520
diff --git a/bfd/elf32-cr16.c b/bfd/elf32-cr16.c
index 8a3775efc07..c1fc361f9de 100644
--- a/bfd/elf32-cr16.c
+++ b/bfd/elf32-cr16.c
@@ -922,10 +922,7 @@ cr16_elf_final_link_relocate (reloc_howto_type *howto,
      as signed or unsigned.  */
   check = Rvalue >> howto->rightshift;
 
-  /* Assumes two's complement.  This expression avoids
-     overflow if howto->bitsize is the number of bits in
-     bfd_vma.  */
-  reloc_bits = (((1 << (howto->bitsize - 1)) - 1) << 1) | 1;
+  reloc_bits = ((bfd_vma) 1 << (howto->bitsize - 1) << 1) - 1;
 
   /* For GOT and GOTC relocs no boundary checks applied.  */
   if (!((r_type == R_CR16_GOT_REGREL20)