linux-kernel - [PATCH -mm] prctl: Return -EFAULT on auxv fetching failure

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Date:	Wed, 27 Aug 2014 15:03:53 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Dan Carpenter <dan.carpenter@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH -mm] prctl: Return -EFAULT on auxv fetching failure

Dan reported that returning bytes left if copy_from_user failed
is a bad option, return traditional -EFAULT instead.

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
---
Dan, this is not for current linux-next, but for Andrew's -mm
queue, since he has prctl code already updated with v4 of the
former patch.

 kernel/sys.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Index: linux-2.6.git/kernel/sys.c
===================================================================
--- linux-2.6.git.orig/kernel/sys.c
+++ linux-2.6.git/kernel/sys.c
@@ -1814,11 +1814,10 @@ static int prctl_set_mm_map(int opt, con
 
 	if (prctl_map.auxv_size) {
 		memset(user_auxv, 0, sizeof(user_auxv));
-		error = copy_from_user(user_auxv,
-				       (const void __user *)prctl_map.auxv,
-				       prctl_map.auxv_size);
-		if (error)
-			return error;
+		if (copy_from_user(user_auxv,
+				   (const void __user *)prctl_map.auxv,
+				   prctl_map.auxv_size))
+			return -EFAULT;
 
 		/* Last entry must be AT_NULL as specification requires */
 		user_auxv[AT_VECTOR_SIZE - 2] = AT_NULL;
--
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