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From:   Edward AD <twuufnxlz@gmail.com>
To:     syzbot+9cf75dc581fb4307d6dd@syzkaller.appspotmail.com
Cc:     adilger.kernel@dilger.ca, ebiggers@google.com,
        krisman@collabora.com, linux-ext4@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzkaller-bugs@googlegroups.com, tytso@mit.edu
Subject: [PATCH] unicode: add s_encoding null ptr check in utf8ncursor
Date:   Wed, 20 Sep 2023 19:20:16 +0800
Message-ID: <20230920112015.829124-2-twuufnxlz@gmail.com>
In-Reply-To: <0000000000001f0b970605c39a7e@google.com>
References: <0000000000001f0b970605c39a7e@google.com>
MIME-Version: 1.0
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When init struct utf8cursor *u8c in utf8ncursor(), we need check um is
valid.

Reported-and-tested-by: syzbot+9cf75dc581fb4307d6dd@syzkaller.appspotmail.com
Fixes: b81427939590 ("ext4: remove redundant checks of s_encoding")
Signed-off-by: Edward AD <twuufnxlz@gmail.com>
---
 fs/unicode/utf8-norm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/unicode/utf8-norm.c b/fs/unicode/utf8-norm.c
index 768f8ab448b8..906b639b2f38 100644
--- a/fs/unicode/utf8-norm.c
+++ b/fs/unicode/utf8-norm.c
@@ -422,6 +422,10 @@ int utf8ncursor(struct utf8cursor *u8c, const struct unicode_map *um,
 {
 	if (!s)
 		return -1;
+
+	if (IS_ERR_OR_NULL(um))
+		return -1;
+
 	u8c->um = um;
 	u8c->n = n;
 	u8c->s = s;
-- 
2.25.1