From: Denys Vlasenko <dvlasenk@redhat.com>
Date: Thu, 30 Jul 2015 11:29:20 +0000 (+0200)
Subject: net.c: recvfrom fixes
X-Git-Tag: v4.11~316
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=383386de73799a7c977e729c1e104ba6d6b3630c;p=strace

net.c: recvfrom fixes

This change fixes these three problems (before/after is shown):

On interrupted syscall, flags are not decoded:

    -recvfrom(3, 0x7fff0a41e306, 10, 2, 0, 0) = ? ERESTARTSYS
    +recvfrom(3, 0x7fff0a41e306, 10, MSG_PEEK, 0, 0) = ? ERESTARTSYS

If peer address is unavalable (example: anon sockets from socketpair()),
kernel returns socklen of 0, but we ignore that and show bogus sockaddr data:

    -recvfrom(3, "123456789\0", 10, MSG_PEEK, {sa_family=0x7777 /* AF_??? */, sa_data="wwwwwwwwwwwwww"}, [0]) = 10
    +recvfrom(3, "123456789\0", 10, MSG_PEEK, 0x7ffde6edf760, [0]) = 10

SYS_FUNC(recvfrom) passes address of fromlen, not fromlen, to printsock():

    -               printsock(tcp, tcp->u_arg[4], tcp->u_arg[5]);
    +               printsock(tcp, tcp->u_arg[4], fromlen);

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
---

diff --git a/net.c b/net.c
index a4a2de54..7412519b 100644
--- a/net.c
+++ b/net.c
@@ -146,7 +146,12 @@ printsock(struct tcb *tcp, long addr, int addrlen)
 	} addrbuf;
 	char string_addr[100];
 
-	if (addrlen < 2 || addrlen > (int) sizeof(addrbuf))
+	if (addrlen < 2) {
+		tprintf("%#lx", addr);
+		return;
+	}
+
+	if (addrlen > (int) sizeof(addrbuf))
 		addrlen = sizeof(addrbuf);
 
 	memset(&addrbuf, 0, sizeof(addrbuf));
@@ -807,28 +812,31 @@ SYS_FUNC(recvfrom)
 		printfd(tcp, tcp->u_arg[0]);
 		tprints(", ");
 	} else {
+		/* buf */
 		if (syserror(tcp)) {
-			tprintf("%#lx, %lu, %lu, %#lx, %#lx",
-				tcp->u_arg[1], tcp->u_arg[2], tcp->u_arg[3],
-				tcp->u_arg[4], tcp->u_arg[5]);
-			return 0;
+			tprintf("%#lx",	tcp->u_arg[1]);
+		} else {
+			printstr(tcp, tcp->u_arg[1], tcp->u_rval);
 		}
-		/* buf */
-		printstr(tcp, tcp->u_arg[1], tcp->u_rval);
 		/* len */
 		tprintf(", %lu, ", tcp->u_arg[2]);
 		/* flags */
 		printflags(msg_flags, tcp->u_arg[3], "MSG_???");
-		/* from address, len */
+		if (syserror(tcp)) {
+			tprintf(", %#lx, %#lx", tcp->u_arg[4], tcp->u_arg[5]);
+			return 0;
+		}
 		tprints(", ");
 		if (!tcp->u_arg[4] || !tcp->u_arg[5] ||
 		    umove(tcp, tcp->u_arg[5], &fromlen) < 0) {
+			/* from address, len */
 			printaddr(tcp->u_arg[4]);
 			tprints(", ");
 			printaddr(tcp->u_arg[5]);
 			return 0;
 		}
-		printsock(tcp, tcp->u_arg[4], tcp->u_arg[5]);
+		/* from address */
+		printsock(tcp, tcp->u_arg[4], fromlen);
 		/* from length */
 		tprintf(", [%u]", fromlen);
 	}