linux-kernel - [PATCH] Pass correct length to strnlen

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Message-ID: <4E680EBC.4000804@gmail.com>
Date:	Thu, 08 Sep 2011 10:39:24 +1000
From:	Ryan Mallon <rmallon@...il.com>
To:	Mark Salter <msalter@...hat.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] Pass correct length to strnlen_user in fs/exec.c

Mail client was still mis-behaving. Should be fixed now.

---
Replace valid_arg_len function in fs/exec.c with max_arg_len function
and pass the correct length to strnlen_user.

Signed-off-by: Ryan Mallon <rmallon@...il.com>
---

diff --git a/fs/exec.c b/fs/exec.c
index e19588c..12d2f7f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -296,9 +296,9 @@ err:
 	return err;
 }
 
-static bool valid_arg_len(struct linux_binprm *bprm, long len)
+static long max_arg_len(struct linux_binprm *bprm)
 {
-	return len <= MAX_ARG_STRLEN;
+	return MAX_ARG_STRLEN;
 }
 
 #else
@@ -354,9 +354,9 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
 	return 0;
 }
 
-static bool valid_arg_len(struct linux_binprm *bprm, long len)
+static long max_arg_len(struct linux_binprm *bprm)
 {
-	return len <= bprm->p;
+	return bprm->p;
 }
 
 #endif /* CONFIG_MMU */
@@ -474,18 +474,19 @@ static int copy_strings(int argc, struct user_arg_ptr argv,
 		const char __user *str;
 		int len;
 		unsigned long pos;
+		long max_len = max_arg_len(bprm);
 
 		ret = -EFAULT;
 		str = get_user_arg_ptr(argv, argc);
 		if (IS_ERR(str))
 			goto out;
 
-		len = strnlen_user(str, MAX_ARG_STRLEN);
-		if (!len || len > MAX_ARG_STRLEN)
+		len = strnlen_user(str, max_len);
+		if (!len)
 			goto out;
 
 		ret = -E2BIG;
-		if (!valid_arg_len(bprm, len))
+		if (len > max_len)
 			goto out;
 
 		/* We're going to work our way backwords. */

--
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