From: Elvira Khabirova <lineprinter0@gmail.com>
Date: Wed, 19 Aug 2015 03:06:29 +0000 (+0300)
Subject: ipc_msg.c: fix multiple personalities support in msgrcv ipc subcall
X-Git-Tag: v4.11~263
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d079fb19f239be3dfb7c7062ce7cae6e908a4f92;p=strace

ipc_msg.c: fix multiple personalities support in msgrcv ipc subcall

When msgrcv syscall is an ipc subcall, msgp (pointer to struct msgbuf)
and msgtyp (message type) syscall arguments are passed via proxy
structure which definition significantly depends on tracee's
wordsize.

* ipc_msg.c (fetch_msgrcv_args): New function.
(sys_msgrcv): Use it.
---

diff --git a/ipc_msg.c b/ipc_msg.c
index fb126f53..5052eace 100644
--- a/ipc_msg.c
+++ b/ipc_msg.c
@@ -81,22 +81,35 @@ tprint_msgrcv(struct tcb *tcp, const long addr, const unsigned long count,
 	tprintf("%ld, ", msgtyp);
 }
 
+static int
+fetch_msgrcv_args(struct tcb *tcp, const long addr, long *pair)
+{
+	if (current_wordsize == sizeof(long)) {
+		if (umoven_or_printaddr(tcp, addr, 2 * sizeof(long), pair))
+			return -1;
+	} else {
+		unsigned int tmp[2];
+
+		if (umove_or_printaddr(tcp, addr, &tmp))
+			return -1;
+		pair[0] = tmp[0];
+		pair[1] = tmp[1];
+	}
+	return 0;
+}
+
 SYS_FUNC(msgrcv)
 {
 	if (entering(tcp)) {
 		tprintf("%d, ", (int) tcp->u_arg[0]);
 	} else {
 		if (indirect_ipccall(tcp)) {
-			struct ipc_wrapper {
-				struct msgbuf *msgp;
-				long msgtyp;
-			} tmp;
+			long pair[2];
 
-			if (umove_or_printaddr(tcp, tcp->u_arg[3], &tmp))
+			if (fetch_msgrcv_args(tcp, tcp->u_arg[3], pair))
 				tprintf(", %lu, ", tcp->u_arg[1]);
 			else
-				tprint_msgrcv(tcp, (long) tmp.msgp,
-					tcp->u_arg[1], tmp.msgtyp);
+				tprint_msgrcv(tcp, pair[0], tcp->u_arg[1], pair[1]);
 			printflags(ipc_msg_flags, tcp->u_arg[2], "MSG_???");
 		} else {
 			tprint_msgrcv(tcp, tcp->u_arg[1],