Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6

* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6:
  [S390] MAINTAINERS: Update zcrypt driver entry
  [S390] Randomize PIEs
  [S390] Randomise the brk region
  [S390] Add is_32bit_task() helper function
  [S390] Randomize lower bits of stack address
  [S390] Randomize mmap start address
  [S390] Rearrange mmap.c
  [S390] Enable flexible mmap layout for 64 bit processes
  [S390] vdso: dont map at mmap_base
  [S390] reduce miminum gap between stack and mmap_base
  [S390] mmap: consider stack address randomization
  [S390] Update default configuration
  [S390] cio: path_event overindication after resume

1 files changed, 31 insertions, 18 deletions

diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 869efba..c9a9f7f 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -27,17 +27,44 @@
 #include <linux/personality.h>
 #include <linux/mm.h>
 #include <linux/module.h>
+#include <linux/random.h>
 #include <asm/pgalloc.h>
 #include <asm/compat.h>
 
+static unsigned long stack_maxrandom_size(void)
+{
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
+	if (current->personality & ADDR_NO_RANDOMIZE)
+		return 0;
+	return STACK_RND_MASK << PAGE_SHIFT;
+}
+
 /*
  * Top of mmap area (just below the process stack).
  *
- * Leave an at least ~128 MB hole.
+ * Leave at least a ~32 MB hole.
  */
-#define MIN_GAP (128*1024*1024)
+#define MIN_GAP (32*1024*1024)
 #define MAX_GAP (STACK_TOP/6*5)
 
+static inline int mmap_is_legacy(void)
+{
+	if (current->personality & ADDR_COMPAT_LAYOUT)
+		return 1;
+	if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
+		return 1;
+	return sysctl_legacy_va_layout;
+}
+
+static unsigned long mmap_rnd(void)
+{
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
+	/* 8MB randomization for mmap_base */
+	return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
+}
+
 static inline unsigned long mmap_base(void)
 {
 	unsigned long gap = rlimit(RLIMIT_STACK);
@@ -46,22 +73,8 @@ static inline unsigned long mmap_base(void)
 		gap = MIN_GAP;
 	else if (gap > MAX_GAP)
 		gap = MAX_GAP;
-
-	return STACK_TOP - (gap & PAGE_MASK);
-}
-
-static inline int mmap_is_legacy(void)
-{
-#ifdef CONFIG_64BIT
-	/*
-	 * Force standard allocation for 64 bit programs.
-	 */
-	if (!is_compat_task())
-		return 1;
-#endif
-	return sysctl_legacy_va_layout ||
-	    (current->personality & ADDR_COMPAT_LAYOUT) ||
-	    rlimit(RLIMIT_STACK) == RLIM_INFINITY;
+	gap &= PAGE_MASK;
+	return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
 }
 
 #ifndef CONFIG_64BIT