From: Rich Felker <dalias@aerifal.cx>
Date: Sun, 4 Sep 2011 14:29:04 +0000 (-0400)
Subject: memstreams: fix incorrect handling of file pos > current size
X-Git-Tag: v0.8.0~16
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=7ee3dcb3c603b20fcd4547ffb00e11701c6d1cf4;p=oweals%2Fmusl.git

memstreams: fix incorrect handling of file pos > current size

the addition is safe and cannot overflow because both operands are
positive when considered as signed quantities.
---

diff --git a/src/stdio/open_memstream.c b/src/stdio/open_memstream.c
index 7fc16204..687e818d 100644
--- a/src/stdio/open_memstream.c
+++ b/src/stdio/open_memstream.c
@@ -32,8 +32,8 @@ static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
 		f->wpos = f->wbase;
 		if (ms_write(f, f->wbase, len2) < len2) return 0;
 	}
-	if (len >= c->space - c->pos) {
-		len2 = 2*c->space+1 | c->space+len+1;
+	if (len + c->pos >= c->space) {
+		len2 = 2*c->space+1 | c->pos+len+1;
 		newbuf = realloc(c->buf, len2);
 		if (!newbuf) return 0;
 		*c->bufp = c->buf = newbuf;
diff --git a/src/stdio/open_wmemstream.c b/src/stdio/open_wmemstream.c
index 0db77416..a830b143 100644
--- a/src/stdio/open_wmemstream.c
+++ b/src/stdio/open_wmemstream.c
@@ -30,8 +30,8 @@ static size_t wms_write(FILE *f, const unsigned char *buf, size_t len)
 	struct cookie *c = f->cookie;
 	size_t len2;
 	wchar_t *newbuf;
-	if (len >= c->space - c->pos) {
-		len2 = 2*c->space+1 | c->space+len+1;
+	if (len + c->pos >= c->space) {
+		len2 = 2*c->space+1 | c->pos+len+1;
 		if (len2 > SSIZE_MAX/4) return 0;
 		newbuf = realloc(c->buf, len2*4);
 		if (!newbuf) return 0;