linux-kernel - [PATCH 4.9 141/171] net: socket: fix a missing-check bug

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20181108215137.187831317@linuxfoundation.org>
Date:   Thu,  8 Nov 2018 13:51:51 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Wenwen Wang <wang6495@....edu>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 141/171] net: socket: fix a missing-check bug

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Wenwen Wang <wang6495@....edu>

[ Upstream commit b6168562c8ce2bd5a30e213021650422e08764dc ]

In ethtool_ioctl(), the ioctl command 'ethcmd' is checked through a switch
statement to see whether it is necessary to pre-process the ethtool
structure, because, as mentioned in the comment, the structure
ethtool_rxnfc is defined with padding. If yes, a user-space buffer 'rxnfc'
is allocated through compat_alloc_user_space(). One thing to note here is
that, if 'ethcmd' is ETHTOOL_GRXCLSRLALL, the size of the buffer 'rxnfc' is
partially determined by 'rule_cnt', which is actually acquired from the
user-space buffer 'compat_rxnfc', i.e., 'compat_rxnfc->rule_cnt', through
get_user(). After 'rxnfc' is allocated, the data in the original user-space
buffer 'compat_rxnfc' is then copied to 'rxnfc' through copy_in_user(),
including the 'rule_cnt' field. However, after this copy, no check is
re-enforced on 'rxnfc->rule_cnt'. So it is possible that a malicious user
race to change the value in the 'compat_rxnfc->rule_cnt' between these two
copies. Through this way, the attacker can bypass the previous check on
'rule_cnt' and inject malicious data. This can cause undefined behavior of
the kernel and introduce potential security risk.

This patch avoids the above issue via copying the value acquired by
get_user() to 'rxnfc->rule_cn', if 'ethcmd' is ETHTOOL_GRXCLSRLALL.

Signed-off-by: Wenwen Wang <wang6495@....edu>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/socket.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/net/socket.c
+++ b/net/socket.c
@@ -2774,9 +2774,14 @@ static int ethtool_ioctl(struct net *net
 		    copy_in_user(&rxnfc->fs.ring_cookie,
 				 &compat_rxnfc->fs.ring_cookie,
 				 (void __user *)(&rxnfc->fs.location + 1) -
-				 (void __user *)&rxnfc->fs.ring_cookie) ||
-		    copy_in_user(&rxnfc->rule_cnt, &compat_rxnfc->rule_cnt,
-				 sizeof(rxnfc->rule_cnt)))
+				 (void __user *)&rxnfc->fs.ring_cookie))
+			return -EFAULT;
+		if (ethcmd == ETHTOOL_GRXCLSRLALL) {
+			if (put_user(rule_cnt, &rxnfc->rule_cnt))
+				return -EFAULT;
+		} else if (copy_in_user(&rxnfc->rule_cnt,
+					&compat_rxnfc->rule_cnt,
+					sizeof(rxnfc->rule_cnt)))
 			return -EFAULT;
 	}