[patch 9/9] udplite: Protection against coverage value wrap-around

[Greg KH]

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

------------------
From: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>

[ Upstream commit 47112e25da41d9059626033986dc3353e101f815 ]

This patch clamps the cscov setsockopt values to a maximum of 0xFFFF.

Setsockopt values greater than 0xffff can cause an unwanted
wrap-around.  Further, IPv6 jumbograms are not supported (RFC 3838,
3.5), so that values greater than 0xffff are not even useful.

Further changes: fixed a typo in the documentation.

[ Add USHORT_MAX from upstream to linux/kernel.h -DaveM ]

Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 Documentation/networking/udplite.txt |    2 +-
 include/linux/kernel.h               |    1 +
 net/ipv4/udp.c                       |    4 ++++
 3 files changed, 6 insertions(+), 1 deletion(-)

--- a/Documentation/networking/udplite.txt
+++ b/Documentation/networking/udplite.txt
@@ -148,7 +148,7 @@
         getsockopt(sockfd, SOL_SOCKET, SO_NO_CHECK, &value, ...);
 
   is meaningless (as in TCP). Packets with a zero checksum field are
-  illegal (cf. RFC 3828, sec. 3.1) will be silently discarded.
+  illegal (cf. RFC 3828, sec. 3.1) and will be silently discarded.
 
   4) Fragmentation
 
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -20,6 +20,7 @@
 extern const char linux_banner[];
 extern const char linux_proc_banner[];
 
+#define USHORT_MAX	((u16)(~0U))
 #define INT_MAX		((int)(~0U>>1))
 #define INT_MIN		(-INT_MAX - 1)
 #define UINT_MAX	(~0U)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1325,6 +1325,8 @@ int udp_lib_setsockopt(struct sock *sk, 
 			return -ENOPROTOOPT;
 		if (val != 0 && val < 8) /* Illegal coverage: use default (8) */
 			val = 8;
+		else if (val > USHORT_MAX)
+			val = USHORT_MAX;
 		up->pcslen = val;
 		up->pcflag |= UDPLITE_SEND_CC;
 		break;
@@ -1337,6 +1339,8 @@ int udp_lib_setsockopt(struct sock *sk, 
 			return -ENOPROTOOPT;
 		if (val != 0 && val < 8) /* Avoid silly minimal values.       */
 			val = 8;
+		else if (val > USHORT_MAX)
+			val = USHORT_MAX;
 		up->pcrlen = val;
 		up->pcflag |= UDPLITE_RECV_CC;
 		break;

-- 
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