linux-kernel - [147/205] ethtool: Fix potential user buffer overflow for ETHTOOL

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Message-Id: <20100730175147.325919862@clark.site>
Date:	Fri, 30 Jul 2010 10:52:44 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Ben Hutchings <bhutchings@...arflare.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [147/205] ethtool: Fix potential user buffer overflow for ETHTOOL_{G, S}RXFH

2.6.34-stable review patch.  If anyone has any objections, please let us know.

------------------

commit bf988435bd5b53529f4408a8efb1f433f6ddfda9 upstream.

struct ethtool_rxnfc was originally defined in 2.6.27 for the
ETHTOOL_{G,S}RXFH command with only the cmd, flow_type and data
fields.  It was then extended in 2.6.30 to support various additional
commands.  These commands should have been defined to use a new
structure, but it is too late to change that now.

Since user-space may still be using the old structure definition
for the ETHTOOL_{G,S}RXFH commands, and since they do not need the
additional fields, only copy the originally defined fields to and
from user-space.

Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 include/linux/ethtool.h |    2 ++
 net/core/ethtool.c      |   38 +++++++++++++++++++++++++++++---------
 2 files changed, 31 insertions(+), 9 deletions(-)

--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -378,6 +378,8 @@ struct ethtool_rxnfc {
 	__u32				flow_type;
 	/* The rx flow hash value or the rule DB size */
 	__u64				data;
+	/* The following fields are not valid and must not be used for
+	 * the ETHTOOL_{G,X}RXFH commands. */
 	struct ethtool_rx_flow_spec	fs;
 	__u32				rule_cnt;
 	__u32				rule_locs[0];
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -300,22 +300,34 @@ out:
 	return ret;
 }
 
-static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev, void __user *useraddr)
+static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
+						u32 cmd, void __user *useraddr)
 {
-	struct ethtool_rxnfc cmd;
+	struct ethtool_rxnfc info;
+	size_t info_size = sizeof(info);
 
 	if (!dev->ethtool_ops->set_rxnfc)
 		return -EOPNOTSUPP;
 
-	if (copy_from_user(&cmd, useraddr, sizeof(cmd)))
+	/* struct ethtool_rxnfc was originally defined for
+	 * ETHTOOL_{G,S}RXFH with only the cmd, flow_type and data
+	 * members.  User-space might still be using that
+	 * definition. */
+	if (cmd == ETHTOOL_SRXFH)
+		info_size = (offsetof(struct ethtool_rxnfc, data) +
+			     sizeof(info.data));
+
+	if (copy_from_user(&info, useraddr, info_size))
 		return -EFAULT;
 
-	return dev->ethtool_ops->set_rxnfc(dev, &cmd);
+	return dev->ethtool_ops->set_rxnfc(dev, &info);
 }
 
-static noinline_for_stack int ethtool_get_rxnfc(struct net_device *dev, void __user *useraddr)
+static noinline_for_stack int ethtool_get_rxnfc(struct net_device *dev,
+						u32 cmd, void __user *useraddr)
 {
 	struct ethtool_rxnfc info;
+	size_t info_size = sizeof(info);
 	const struct ethtool_ops *ops = dev->ethtool_ops;
 	int ret;
 	void *rule_buf = NULL;
@@ -323,7 +335,15 @@ static noinline_for_stack int ethtool_ge
 	if (!ops->get_rxnfc)
 		return -EOPNOTSUPP;
 
-	if (copy_from_user(&info, useraddr, sizeof(info)))
+	/* struct ethtool_rxnfc was originally defined for
+	 * ETHTOOL_{G,S}RXFH with only the cmd, flow_type and data
+	 * members.  User-space might still be using that
+	 * definition. */
+	if (cmd == ETHTOOL_GRXFH)
+		info_size = (offsetof(struct ethtool_rxnfc, data) +
+			     sizeof(info.data));
+
+	if (copy_from_user(&info, useraddr, info_size))
 		return -EFAULT;
 
 	if (info.cmd == ETHTOOL_GRXCLSRLALL) {
@@ -341,7 +361,7 @@ static noinline_for_stack int ethtool_ge
 		goto err_out;
 
 	ret = -EFAULT;
-	if (copy_to_user(useraddr, &info, sizeof(info)))
+	if (copy_to_user(useraddr, &info, info_size))
 		goto err_out;
 
 	if (rule_buf) {
@@ -1492,12 +1512,12 @@ int dev_ethtool(struct net *net, struct
 	case ETHTOOL_GRXCLSRLCNT:
 	case ETHTOOL_GRXCLSRULE:
 	case ETHTOOL_GRXCLSRLALL:
-		rc = ethtool_get_rxnfc(dev, useraddr);
+		rc = ethtool_get_rxnfc(dev, ethcmd, useraddr);
 		break;
 	case ETHTOOL_SRXFH:
 	case ETHTOOL_SRXCLSRLDEL:
 	case ETHTOOL_SRXCLSRLINS:
-		rc = ethtool_set_rxnfc(dev, useraddr);
+		rc = ethtool_set_rxnfc(dev, ethcmd, useraddr);
 		break;
 	case ETHTOOL_GGRO:
 		rc = ethtool_get_gro(dev, useraddr);


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