exec: load_script: kill the onstack interp[BINPRM_BUF_SIZE] array

Patch series "exec: binfmt_misc: fix use-after-free, kill
iname[BINPRM_BUF_SIZE]".

It looks like this code was always wrong, then commit 948b701a607f
("binfmt_misc: add persistent opened binary handler for containers")
added more problems.

This patch (of 6):

load_script() can simply use i_name instead, it points into bprm->buf[]
and nobody can change this memory until we call prepare_binprm().

The only complication is that we need to also change the signature of
bprm_change_interp() but this change looks good too.

While at it, do whitespace/style cleanups.

NOTE: the real motivation for this change is that people want to
increase BINPRM_BUF_SIZE, we need to change load_misc_binary() too but
this looks more complicated because afaics it is very buggy.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Kees Cook <[email protected]>
Cc: Travis Gummels <[email protected]>
Cc: Ben Woodard <[email protected]>
Cc: Jim Foraker <[email protected]>
Cc: <[email protected]>
Cc: Al Viro <[email protected]>
Cc: James Bottomley <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index fb44d6180ca0..18d05b5491f3 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -131,7 +131,7 @@ extern int setup_arg_pages(struct linux_binprm * bprm,
 			   int executable_stack);
 extern int transfer_args_to_stack(struct linux_binprm *bprm,
 				  unsigned long *sp_location);
-extern int bprm_change_interp(char *interp, struct linux_binprm *bprm);
+extern int bprm_change_interp(const char *interp, struct linux_binprm *bprm);
 extern int copy_strings_kernel(int argc, const char *const *argv,
 			       struct linux_binprm *bprm);
 extern int prepare_bprm_creds(struct linux_binprm *bprm);