[PATCH] binfmt_elf: randomize PIE binaries (2nd try)

[Marcus Meissner]

Randomizes -pie compiled binaries from PAGE_SIZE up to
ELF_ET_DYN_BASE.

0 -> PAGE_SIZE is excluded to allow NULL ptr accesses
to fail.

Signed-off-by: Marcus Meissner <meissner@xxxxxxx>

----
 binfmt_elf.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- linux-2.6.18/fs/binfmt_elf.c.xx	2006-10-20 10:42:03.000000000 +0200
+++ linux-2.6.18/fs/binfmt_elf.c	2006-10-20 10:51:27.000000000 +0200
@@ -856,7 +856,13 @@
 			 * default mmap base, as well as whatever program they
 			 * might try to exec.  This is because the brk will
 			 * follow the loader, and is not movable.  */
-			load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
+			if (current->flags & PF_RANDOMIZE)
+				load_bias = randomize_range(PAGE_SIZE,
+							    ELF_ET_DYN_BASE,
+							    0);
+			else
+				load_bias = ELF_ET_DYN_BASE;
+			load_bias = ELF_PAGESTART(load_bias - vaddr);
 		}
 
 		error = elf_map(bprm->file, load_bias + vaddr, elf_ppnt,
-
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