dccp: fix bug in updating the GSR

samueljero · Gerrit Renker · commit 763dadd47c88 · 2011-01-07T12:22:43.000+01:00
Currently dccp_check_seqno allows any valid packet to update the Greatest
Sequence Number Received, even if that packet's sequence number is less than
the current GSR. This patch adds a check to make sure that the new packet's
sequence number is greater than GSR.

Signed-off-by: Samuel Jero &lt;sj323707@ohio.edu&gt;
Signed-off-by: Gerrit Renker &lt;gerrit@erg.abdn.ac.uk&gt;
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
@@ -426,7 +426,8 @@ static inline void dccp_update_gsr(struct sock *sk, u64 seq)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
 
-	dp->dccps_gsr = seq;
+	if (after48(seq, dp->dccps_gsr))
+		dp->dccps_gsr = seq;
 	/* Sequence validity window depends on remote Sequence Window (7.5.1) */
 	dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
 	/*

Original file line number	Diff line number	Diff line change
`@@ -426,7 +426,8 @@ static inline void dccp_update_gsr(struct sock *sk, u64 seq)`
`426`	`426`	`{`
`427`	`427`	`struct dccp_sock *dp = dccp_sk(sk);`
`428`	`428`
`429`		`- dp->dccps_gsr = seq;`
	`429`	`+ if (after48(seq, dp->dccps_gsr))`
	`430`	`+ dp->dccps_gsr = seq;`
`430`	`431`	`/* Sequence validity window depends on remote Sequence Window (7.5.1) */`
`431`	`432`	`dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);`
`432`	`433`	`/*`