[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [XEN PATCH 2/4] x86/emulate: move a variable declaration to address MISRA C:2012 Rule 5.3





On 27/07/23 17:06, Jan Beulich wrote:
On 27.07.2023 12:48, Nicola Vetrini wrote:
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2024,15 +2024,15 @@ static int cf_check hvmemul_rep_stos(
switch ( p2mt )
      {
-        unsigned long bytes;
          char *buf;
default:
          /* Allocate temporary buffer. */
          for ( ; ; )
          {
-            bytes = *reps * bytes_per_rep;
-            buf = xmalloc_bytes(bytes);
+            unsigned long bytes_tmp;
+            bytes_tmp = *reps * bytes_per_rep;
+            buf = xmalloc_bytes(bytes_tmp);
              if ( buf || *reps <= 1 )
                  break;
              *reps >>= 1;

This wants dealing with differently - the outer scope variable is unused
(only written to) afaics. Eliminating it will, aiui, address another
violation at the same time. And then the same in hvmemul_rep_movs(), just
that there the variable itself needs to survive. I guess I'll make a
patch ...

Jan

Wouldn't this code at line ~2068 be possibly affected by writing to bytes, if the outer variable is used?

/* Adjust address for reverse store. */
if ( df )
  gpa -= bytes - bytes_per_rep;

rc = hvm_copy_to_guest_phys(gpa, buf, bytes, curr);

You're right about the other violation (R2.1)

--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)



 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.