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

Randomizes -pie compiled binaries from 64k (0x10000) up to ELF_ET_DYN_BASE.

0 -> 64k is excluded to allow NULL ptr accesses to fail.

Signed-off-by: Marcus Meissner <meissner@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index cc72bb43061d..b2efbaead6c3 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -856,7 +856,13 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
                          * 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(0x10000,
+                                                            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,