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