linux-kernel - [PATCH v2] module: report -EFAULT on bytes remaining

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Message-ID: <20120912162102.GA16676@www.outflux.net>
Date:	Wed, 12 Sep 2012 09:21:02 -0700
From:	Kees Cook <keescook@...omium.org>
To:	linux-kernel@...r.kernel.org
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	Fengguang Wu <fengguang.wu@...el.com>,
	kernel-janitors@...r.kernel.org,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Subject: [PATCH v2] module: report -EFAULT on bytes remaining

Caught by smatch:
kernel/module.c:2450 copy_module_from_user() warn: maybe return -EFAULT instead of the bytes remaining?

Fix the check of copy_from_user() to report -EFAULT as was done before.

Reported-by: Fengguang Wu <fengguang.wu@...el.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
Should be applied on top of the finit_module syscall patches.

v2:
 - copy_from_user never returns negative, thanks to Dan Carpenter.
---
 kernel/module.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 0ad03c4..461e7d4 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2440,9 +2440,10 @@ int copy_module_from_user(const void __user *umod, unsigned long len,
 	if (!info->hdr)
 		return -ENOMEM;
 
-	err = copy_from_user(info->hdr, umod, info->len);
-	if (err)
+	if (copy_from_user(info->hdr, umod, info->len) != 0) {
+		err = -EFAULT;
 		goto free_hdr;
+	}
 
 	err = check_info(info);
 	if (err)
-- 
1.7.0.4


-- 
Kees Cook
Chrome OS Security
--
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