kc3-lang/libbsd

2016-01-27T15:10:11

Fix heap buffer overflow in fgetwln() In the function fgetwln() there's a 4 byte heap overflow. There is a while loop that has this check to see whether there's still enough space in the buffer: if (!fb->len || wused > fb->len) { If this is true more memory gets allocated. However this test won't be true if wused == fb->len, but at that point wused already points out of the buffer. Some lines later there's a write to the buffer: fb->wbuf[wused++] = wc; This bug was found with the help of address sanitizer. Warned-by: ASAN Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=93881 Signed-off-by: Guillem Jover <guillem@hadrons.org>

diff --git a/src/fgetwln.c b/src/fgetwln.c
index 9ee0776..aa3f927 100644
--- a/src/fgetwln.c
+++ b/src/fgetwln.c
@@ -60,7 +60,7 @@ fgetwln(FILE *stream, size_t *lenp)
 	fb->fp = stream;
 
 	while ((wc = fgetwc(stream)) != WEOF) {
-		if (!fb->len || wused > fb->len) {
+		if (!fb->len || wused >= fb->len) {
 			wchar_t *wp;
 
 			if (fb->len)