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Commit 1d1dbf81 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

exec: introduce get_user_arg_ptr() helper 



Introduce get_user_arg_ptr() helper, convert count() and copy_strings()
to use it.

No functional changes, preparation. This helper is trivial, it just
reads the pointer from argv/envp user-space array.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
parent bb3c90f0

fs/exec.c

+25 −11
Original line number Original line Diff line number Diff line
@@ -398,6 +398,17 @@ err: 
	return err;

	return err;

}

}





static const char __user *

get_user_arg_ptr(const char __user * const __user *argv, int nr)

{

	const char __user *ptr;



	if (get_user(ptr, argv + nr))

		return ERR_PTR(-EFAULT);



	return ptr;

}



/*

/*

 * count() counts the number of strings in array ARGV.

 * count() counts the number of strings in array ARGV.

 */

 */
@@ -407,13 +418,14 @@ static int count(const char __user * const __user * argv, int max) 




	if (argv != NULL) {

	if (argv != NULL) {

		for (;;) {

		for (;;) {

			const char __user * p;

			const char __user *p = get_user_arg_ptr(argv, i);





			if (get_user(p, argv))

				return -EFAULT;

			if (!p)

			if (!p)

				break;

				break;

			argv++;



			if (IS_ERR(p))

				return -EFAULT;



			if (i++ >= max)

			if (i++ >= max)

				return -E2BIG;

				return -E2BIG;
@@ -443,16 +455,18 @@ static int copy_strings(int argc, const char __user *const __user *argv, 
		int len;

		int len;

		unsigned long pos;

		unsigned long pos;





		if (get_user(str, argv+argc) ||

				!(len = strnlen_user(str, MAX_ARG_STRLEN))) {

		ret = -EFAULT;

		ret = -EFAULT;

		str = get_user_arg_ptr(argv, argc);

		if (IS_ERR(str))

			goto out;



		len = strnlen_user(str, MAX_ARG_STRLEN);

		if (!len)

			goto out;

			goto out;

		}





		if (!valid_arg_len(bprm, len)) {

		ret = -E2BIG;

		ret = -E2BIG;

		if (!valid_arg_len(bprm, len))

			goto out;

			goto out;

		}





		/* We're going to work our way backwords. */

		/* We're going to work our way backwords. */

		pos = bprm->p;

		pos = bprm->p;