From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 6CBB38D0039 for ; Sun, 6 Mar 2011 12:11:01 -0500 (EST) Date: Sun, 6 Mar 2011 18:02:21 +0100 From: Oleg Nesterov Subject: [PATCH v5 1/4] exec: introduce get_user_arg_ptr() helper Message-ID: <20110306170221.GB24175@redhat.com> References: <20110305203040.GA7546@redhat.com> <20110306210334.6CD5.A69D9226@jp.fujitsu.com> <20110306170156.GA24175@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110306170156.GA24175@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: LKML , linux-mm , pageexec@freemail.hu, Solar Designer , Eugene Teo , Brad Spengler , Roland McGrath , Milton Miller , Linus Torvalds , KOSAKI Motohiro 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: Oleg Nesterov Reviewed-by: KOSAKI Motohiro Tested-by: KOSAKI Motohiro --- fs/exec.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) --- 38/fs/exec.c~1_get_arg_ptr 2011-03-06 17:48:00.000000000 +0100 +++ 38/fs/exec.c 2011-03-06 17:51:01.000000000 +0100 @@ -395,6 +395,17 @@ 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. */ @@ -404,13 +415,14 @@ static int count(const char __user * con if (argv != NULL) { for (;;) { - const char __user * p; + const char __user *p = get_user_arg_ptr(argv, i); - if (get_user(p, argv)) - return -EFAULT; if (!p) break; - argv++; + + if (IS_ERR(p)) + return -EFAULT; + if (i++ >= max) return -E2BIG; @@ -440,16 +452,18 @@ static int copy_strings(int argc, const int len; 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; - } - if (!valid_arg_len(bprm, len)) { - ret = -E2BIG; + len = strnlen_user(str, MAX_ARG_STRLEN); + if (!len) + goto out; + + ret = -E2BIG; + if (!valid_arg_len(bprm, len)) goto out; - } /* We're going to work our way backwords. */ pos = bprm->p; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org