From 8e8b63a68c7ec95ef23770813120f4f98c76e08b Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 23 Sep 2009 15:57:06 -0700 Subject: [PATCH] fdpic: ignore the loader's PT_GNU_STACK when calculating the stack size Ignore the loader's PT_GNU_STACK when calculating the stack size, and only consider the executable's PT_GNU_STACK, assuming the executable has one. Currently the behaviour is to take the largest stack size and use that, but that means you can't reduce the stack size in the executable. The loader's stack size should probably only be used when executing the loader directly. WARNING: This patch is slightly dangerous - it may render a system inoperable if the loader's stack size is larger than that of important executables, and the system relies unknowingly on this increasing the size of the stack. Signed-off-by: David Howells Signed-off-by: Mike Frysinger Acked-by: Paul Mundt Cc: Pavel Machek Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/binfmt_elf_fdpic.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 7628547..38502c6 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -283,20 +283,23 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm, } stack_size = exec_params.stack_size; - if (stack_size < interp_params.stack_size) - stack_size = interp_params.stack_size; - if (exec_params.flags & ELF_FDPIC_FLAG_EXEC_STACK) executable_stack = EXSTACK_ENABLE_X; else if (exec_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK) executable_stack = EXSTACK_DISABLE_X; - else if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK) - executable_stack = EXSTACK_ENABLE_X; - else if (interp_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK) - executable_stack = EXSTACK_DISABLE_X; else executable_stack = EXSTACK_DEFAULT; + if (stack_size == 0) { + stack_size = interp_params.stack_size; + if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK) + executable_stack = EXSTACK_ENABLE_X; + else if (interp_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK) + executable_stack = EXSTACK_DISABLE_X; + else + executable_stack = EXSTACK_DEFAULT; + } + retval = -ENOEXEC; if (stack_size == 0) goto error; -- 2.7.4