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authorRich Felker <dalias@aerifal.cx>2011-09-04 10:29:04 -0400
committerRich Felker <dalias@aerifal.cx>2011-09-04 10:29:04 -0400
commit7ee3dcb3c603b20fcd4547ffb00e11701c6d1cf4 (patch)
treede55d7b177cbe5f095ac2745e65e5544254fc067
parentc88f36f55623124d09f48631974ca38aaec00057 (diff)
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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.
-rw-r--r--src/stdio/open_memstream.c4
-rw-r--r--src/stdio/open_wmemstream.c4
2 files changed, 4 insertions, 4 deletions
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;