Fix CVE-2014-0221

snhenson · snhenson · commit d3152655d531 · 2014-06-05T09:04:27.000+01:00
Unnecessary recursion when receiving a DTLS hello request can be used to
crash a DTLS client. Fixed by handling DTLS hello request without recursion.

Thanks to Imre Rad (Search-Lab Ltd.) for discovering this issue.
diff --git a/ssl/d1_both.c b/ssl/d1_both.c
@@ -793,6 +793,7 @@ dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
 	int i,al;
 	struct hm_header_st msg_hdr;
 
+	redo:
 	/* see if we have the required fragment already */
 	if ((frag_len = dtls1_retrieve_buffered_fragment(s,max,ok)) || *ok)
 		{
@@ -851,8 +852,7 @@ dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
 					s->msg_callback_arg);
 			
 			s->init_num = 0;
-			return dtls1_get_message_fragment(s, st1, stn,
-				max, ok);
+			goto redo;
 			}
 		else /* Incorrectly formated Hello request */
 			{

Original file line number	Diff line number	Diff line change
`@@ -793,6 +793,7 @@ dtls1_get_message_fragment(SSL s, int st1, int stn, long max, int ok)`
`793`	`793`	`int i,al;`
`794`	`794`	`struct hm_header_st msg_hdr;`
`795`	`795`
	`796`	`+ redo:`
`796`	`797`	`/* see if we have the required fragment already */`
`797`	`798`	`if ((frag_len = dtls1_retrieve_buffered_fragment(s,max,ok)) \|\| *ok)`
`798`	`799`	`{`
`@@ -851,8 +852,7 @@ dtls1_get_message_fragment(SSL s, int st1, int stn, long max, int ok)`
`851`	`852`	`s->msg_callback_arg);`
`852`	`853`
`853`	`854`	`s->init_num = 0;`
`854`		`- return dtls1_get_message_fragment(s, st1, stn,`
`855`		`- max, ok);`
	`855`	`+ goto redo;`
`856`	`856`	`}`
`857`	`857`	`else /* Incorrectly formated Hello request */`
`858`	`858`	`{`