From 53dfc60094f34bbbfd3410de9165396514fd23c2 Mon Sep 17 00:00:00 2001
From: Michael Drake <tlsa@netsurf-browser.org>
Date: Wed, 5 Jun 2019 21:47:15 +0100
Subject: Media queries: <ratio> isn't allowed to have 0 numerator or
 denominator.

The <ratio> value type is a positive (not zero or negative) <integer>
followed by optional whitespace, followed by a solidus ('/'), followed
by optional whitespace, followed by a positive <integer>. <ratio>s can
be ordered or compared by transforming them into the number obtained
by dividing their first <integer> by their second <integer>.

-- https://www.w3.org/TR/mediaqueries-4/#aspect-ratio
---
 src/parse/mq.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/parse/mq.c b/src/parse/mq.c
index f3510c1..c5e353d 100644
--- a/src/parse/mq.c
+++ b/src/parse/mq.c
@@ -117,6 +117,10 @@ static css_error mq_parse_ratio(
 	num = css__number_from_lwc_string(numerator->idata, true, &num_len);
 	den = css__number_from_lwc_string(token->idata, true, &den_len);
 
+	if (num == 0 || den == 0) {
+		return CSS_INVALID;
+	}
+
 	*ratio = css_divide_fixed(num, den);
 
 	return CSS_OK;
-- 
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