From f70cacbbd7e4c47a153181250382c4481f87c98d Mon Sep 17 00:00:00 2001
From: Tatsuya Kinoshita <tats@debian.org>
Date: Tue, 23 Mar 2021 19:02:12 +0900
Subject: Prevent unneeded memory allocation for language tags in libwc

cf. https://oss-fuzz.com/testcase-detail/6275874304425984
Bug-Chromium: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=31397
---
 libwc/ucs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libwc/ucs.c b/libwc/ucs.c
index 4fe020d..288014e 100644
--- a/libwc/ucs.c
+++ b/libwc/ucs.c
@@ -702,8 +702,13 @@ wtf_push_ucs(Str os, wc_uint32 ucs, wc_status *st)
 	if (! WcOption.use_language_tag)
 	    return;
 	if (ucs == WC_C_LANGUAGE_TAG)
-	    st->tag = Strnew_size(MAX_TAG_LEN);
+	    if (st->tag)
+		Strclear(st->tag);
+	    else
+		st->tag = Strnew_size(MAX_TAG_LEN);
 	else if (ucs == WC_C_CANCEL_TAG) {
+	    if (st->tag)
+		Strfree(st->tag);
 	    st->tag = NULL;
 	    st->ntag = 0;
 	}  else if (st->tag && st->tag->length < MAX_TAG_LEN &&
-- 
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