Bug 90131

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User-Agent: Mozilla/5.0 (X11; U; Linux i686) Gecko/20030313 Galeon/1.3.4

Description of problem:
gcc-3.2.2 corrupts structs if several struct-copy operations are performed in
sequence.  This is a pretty rare occurrence (most people don't use implicit
struct copying), but it meant lately that I had to make some pretty substantial
changes to an analysis program I wrote to get it to run fine on RH8 and RH9. 
(The problem is present in both RH8 and RH9.)  It looks like it is fixed now in GCC:

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&pr=9492

However, I am reporting this as a bug, because it seems to be a serious enough
bug that it could be reported as a security advisory IMHO, so that people are
encouraged to upgrade to gcc-3.2.3.  (You get results in one struct copy that
were contained in the previous copy operation -- a possible security hazard.)

I'm assuming the problem doesn't occur very often, or it would have been fixed
between the GCC versions in RH8 and RH9.

Here's some short code that illustrates the problem.

Thanks!

--


/*

 Compile with: gcc -Wall prog.c -o prog && ./prog

 I'm using gcc version 3.2 20020903 (Red Hat Linux 8.0 3.2-7)
 Also tested on gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5) [RH9]

   Actual output:

    0.0 1.0 0.0
    1.0 0.0 0.0
    1.0 2.0 1.0
    2.0 3.0 4.0

   Expected output:

    2.0 2.0 3.0
    1.0 3.0 3.0
    1.0 2.0 4.0
    2.0 3.0 4.0

*/


#include <stdio.h>


typedef struct {
  double _0, _1, _2;
} POINT;


POINT xform(POINT p) {
  asm("");
  return (POINT) { p._0 + 1.0, p._1 + 2.0, p._2 + 3.0 };
}


int main(void) {
  int i;
  POINT p[4] =
    { xform((POINT) { 1.0, 0.0, 0.0 }),
      xform((POINT) { 0.0, 1.0, 0.0 }),
      xform((POINT) { 0.0, 0.0, 1.0 }),
      xform((POINT) { 1.0, 1.0, 1.0 }) };

  for (i = 0; i < 4; i++)
    printf("    %.1f %.1f %.1f\n", p[i]._0, p[i]._1, p[i]._2);

  return 0;
}




Version-Release number of selected component (if applicable):
gcc-3.2.2-5

How reproducible:
Always

Steps to Reproduce:
As above

Additional info: