[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 <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Dave Jones <[email protected]> Cc: Arjan van de Ven <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
fracktal · Dec 7, 2006 · 59287c0 · 59287c0
1 parent b23984d
commit 59287c0
Showing 1 changed file with 7 additions and 1 deletion.
diff --git 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,