From: Dmitry V. Levin <ldv@altlinux.org>
Date: Sun, 9 Jul 2017 18:43:34 +0000 (+0000)
Subject: net: enhance decoding of MCAST_JOIN_GROUP/MCAST_LEAVE_GROUP
X-Git-Tag: v4.19~290
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=7bcb1dcdbc6a209cc7072975bee5c1ff27fd6393;p=strace

net: enhance decoding of MCAST_JOIN_GROUP/MCAST_LEAVE_GROUP

* net.c (print_group_req): Allow option length greater than
sizeof(struct group_req) to match the kernel behaviour.
When the option length is invalid, print the address.
* NEWS: Mention this.
---

diff --git a/NEWS b/NEWS
index 8e4c6991..fb2e5e76 100644
--- a/NEWS
+++ b/NEWS
@@ -7,7 +7,8 @@ Noteworthy changes in release ?.?? (????-??-??)
   * Enhanced decoding of SO_PEERCRED option of getsockopt syscall.
   * Enhanced decoding of IP_ADD_MEMBERSHIP, IP_DROP_MEMBERSHIP,
     IPV6_ADD_MEMBERSHIP, IPV6_DROP_MEMBERSHIP, IPV6_JOIN_ANYCAST,
-    and IPV6_LEAVE_ANYCAST options of setsockopt syscall.
+    IPV6_LEAVE_ANYCAST, MCAST_JOIN_GROUP, and MCAST_LEAVE_GROUP options
+    of setsockopt syscall.
   * Implemented decoding of linux socket filter programs specified
     for SO_ATTACH_FILTER and SO_ATTACH_REUSEPORT_CBPF socket options.
 
diff --git a/net.c b/net.c
index 6f04b9de..ea1a3eb4 100644
--- a/net.c
+++ b/net.c
@@ -684,20 +684,18 @@ print_mreq6(struct tcb *const tcp, const kernel_ulong_t addr,
 
 #ifdef MCAST_JOIN_GROUP
 static void
-print_group_req(struct tcb *const tcp, const kernel_ulong_t addr, const int len)
+print_group_req(struct tcb *const tcp, const kernel_ulong_t addr,
+		const int len)
 {
 	struct group_req greq;
 
-	if (len != sizeof(greq) ||
-	    umove(tcp, addr, &greq) < 0) {
+	if (len < (int) sizeof(greq)) {
 		printaddr(addr);
-		return;
+	} else if (!umove_or_printaddr(tcp, addr, &greq)) {
+		PRINT_FIELD_IFINDEX("{", greq, gr_interface);
+		PRINT_FIELD_SOCKADDR(", ", greq, gr_group);
+		tprints("}");
 	}
-
-	PRINT_FIELD_IFINDEX("{", greq, gr_interface);
-	PRINT_FIELD_SOCKADDR(", ", greq, gr_group);
-	tprints("}");
-
 }
 #endif /* MCAST_JOIN_GROUP */