linux-kernel - [ 139/180] dccp: check ccid before dereferencing

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Message-Id: <20121001225203.502626725@1wt.eu>
Date:	Tue, 02 Oct 2012 00:54:16 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Mathias Krause <minipli@...glemail.com>,
	Gerrit Renker <gerrit@....abdn.ac.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Willy Tarreau <w@....eu>
Subject: [ 139/180] dccp: check ccid before dereferencing

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

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

From: Mathias Krause <minipli@...glemail.com>

commit 276bdb82dedb290511467a5a4fdbe9f0b52dce6f upstream.

ccid_hc_rx_getsockopt() and ccid_hc_tx_getsockopt() might be called with
a NULL ccid pointer leading to a NULL pointer dereference. This could
lead to a privilege escalation if the attacker is able to map page 0 and
prepare it with a fake ccid_ops pointer.

Signed-off-by: Mathias Krause <minipli@...glemail.com>
Cc: Gerrit Renker <gerrit@....abdn.ac.uk>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Willy Tarreau <w@....eu>
---
 net/dccp/ccid.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/dccp/ccid.h b/net/dccp/ccid.h
index facedd2..ab260b0 100644
--- a/net/dccp/ccid.h
+++ b/net/dccp/ccid.h
@@ -214,7 +214,7 @@ static inline int ccid_hc_rx_getsockopt(struct ccid *ccid, struct sock *sk,
 					u32 __user *optval, int __user *optlen)
 {
 	int rc = -ENOPROTOOPT;
-	if (ccid->ccid_ops->ccid_hc_rx_getsockopt != NULL)
+	if (ccid != NULL && ccid->ccid_ops->ccid_hc_rx_getsockopt != NULL)
 		rc = ccid->ccid_ops->ccid_hc_rx_getsockopt(sk, optname, len,
 						 optval, optlen);
 	return rc;
@@ -225,7 +225,7 @@ static inline int ccid_hc_tx_getsockopt(struct ccid *ccid, struct sock *sk,
 					u32 __user *optval, int __user *optlen)
 {
 	int rc = -ENOPROTOOPT;
-	if (ccid->ccid_ops->ccid_hc_tx_getsockopt != NULL)
+	if (ccid != NULL && ccid->ccid_ops->ccid_hc_tx_getsockopt != NULL)
 		rc = ccid->ccid_ops->ccid_hc_tx_getsockopt(sk, optname, len,
 						 optval, optlen);
 	return rc;
-- 
1.7.2.1.45.g54fbc



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