Guest OS : Linux 2.6.15-1.2054_FC5 i686 (Fedora Core 5 i386)
Host OS: Linux 2.6.12-10-amd64-k8 #1 x86_64 (Ubuntu 5.10 amd64)
QEMU Version : today CVS compiled with kqemu support
KQEMU : 1.3.0pre6
Binary used : qemu-system-x86-64 (so kqemu user-mode is used)

I'm running the simple C code attached. With kqemu user-mode, this fails 
(sigsegv) with the following warning in dmesg :

audit(1146505373.813:12): avc:  denied { execheap } for pid=1860 
comm="selfmodifying scontext=user_u:system_r:unconfined_t:s0 
tcontext=user_u:system_r:unconfined_t:s0 tclass=process
Erreur de segmentation

Without kqemu enabled, it runs fine.

#define _XOPEN_SOURCE 600
#include <sys/mman.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char** argv)
{
  int pagesize = getpagesize();
  unsigned char* addr = NULL;
  posix_memalign((void**)&addr, pagesize, pagesize);
  mprotect(addr, pagesize, PROT_WRITE | PROT_READ | PROT_EXEC);
  addr[0] = 0x8b; addr[1] = 0x44; addr[2] = 0x24; addr[3] = 0x04; /* mov    0x4(%esp),%eax */
  addr[4] = 0x83; addr[5] = 0xc0; addr[6] = 0x01; /* add    $0x1,%eax */
  addr[7] = 0xc3; /* ret */
  
  printf("10+1=%d\n", ((int (*)(int))addr)(10));
  free(addr);
  return 0;
}
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