exec: remove argv_len from struct linux_binprm

I noticed that 2.6.24.2 calculates bprm->argv_len at do_execve().  But it
doesn't update bprm->argv_len after "remove_arg_zero() +
copy_strings_kernel()" at load_script() etc.

audit_bprm() is called from search_binary_handler() and
search_binary_handler() is called from load_script() etc.  Thus, I think the
condition check

  if (bprm->argv_len > (audit_argv_kb << 10))
          return -E2BIG;

in audit_bprm() might return wrong result when strlen(removed_arg) !=
strlen(spliced_args).  Why not update bprm->argv_len at load_script() etc.  ?

By the way, 2.6.25-rc3 seems to not doing the condition check.  Is the field
bprm->argv_len no longer needed?

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Ollie Wild <aaw@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/exec.c

@@ -1268,7 +1268,6 @@ int do_execve(char * filename,
 {
 	struct linux_binprm *bprm;
 	struct file *file;
-	unsigned long env_p;
 	struct files_struct *displaced;
 	int retval;
 
@@ -1321,11 +1320,9 @@ int do_execve(char * filename,
 	if (retval < 0)
 		goto out;
 
-	env_p = bprm->p;
 	retval = copy_strings(bprm->argc, argv, bprm);
 	if (retval < 0)
 		goto out;
-	bprm->argv_len = env_p - bprm->p;
 
 	retval = search_binary_handler(bprm,regs);
 	if (retval >= 0) {

include/linux/binfmts.h

@@ -48,7 +48,6 @@ struct linux_binprm{
 	unsigned interp_flags;
 	unsigned interp_data;
 	unsigned long loader, exec;
-	unsigned long argv_len;
 };
 
 #define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0