From: Eugene Syromyatnikov <evgsyr@gmail.com>
Date: Mon, 19 Dec 2016 22:13:21 +0000 (+0300)
Subject: x32: fix decoding of 3rd argument of preadv* and pwritev* syscalls
X-Git-Tag: v4.16~323
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0c6f7555256a0eb0f3e728bed53964dcb565b2e7;p=strace

x32: fix decoding of 3rd argument of preadv* and pwritev* syscalls

In x32 personality these syscalls use compat type for the 3rd argument,
therefore it has to be truncated there.

* io.c (do_preadv, do_pwritev): Truncate tcp->u_arg[2] using
widen_to_ulong.
---

diff --git a/io.c b/io.c
index 53419ed8..713a1ce4 100644
--- a/io.c
+++ b/io.c
@@ -222,10 +222,12 @@ do_preadv(struct tcb *tcp, const int flags_arg)
 		printfd(tcp, tcp->u_arg[0]);
 		tprints(", ");
 	} else {
-		tprint_iov_upto(tcp, tcp->u_arg[2], tcp->u_arg[1],
+		unsigned long len = widen_to_ulong(tcp->u_arg[2]);
+
+		tprint_iov_upto(tcp, len, tcp->u_arg[1],
 				syserror(tcp) ? IOV_DECODE_ADDR :
 				IOV_DECODE_STR, tcp->u_rval);
-		tprintf(", %lu, ", tcp->u_arg[2]);
+		tprintf(", %lu, ", len);
 		print_lld_from_low_high_val(tcp, 3);
 		if (flags_arg >= 0) {
 			tprints(", ");
@@ -248,10 +250,12 @@ SYS_FUNC(preadv2)
 static int
 do_pwritev(struct tcb *tcp, const int flags_arg)
 {
+	unsigned long len = widen_to_ulong(tcp->u_arg[2]);
+
 	printfd(tcp, tcp->u_arg[0]);
 	tprints(", ");
-	tprint_iov(tcp, tcp->u_arg[2], tcp->u_arg[1], IOV_DECODE_STR);
-	tprintf(", %lu, ", tcp->u_arg[2]);
+	tprint_iov(tcp, len, tcp->u_arg[1], IOV_DECODE_STR);
+	tprintf(", %lu, ", len);
 	print_lld_from_low_high_val(tcp, 3);
 	if (flags_arg >= 0) {
 		tprints(", ");