linux-kernel - [PATCH] cifs: fix an OOB issue in cifsConvertToUTF16()

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Message-Id: <20250705161515.12202-1-dinghui@sangfor.com.cn>
Date: Sun,  6 Jul 2025 00:15:15 +0800
From: Ding Hui <dinghui@...gfor.com.cn>
To: sfrench@...ba.org,
	pc@...guebit.org,
	ronniesahlberg@...il.com,
	sprasad@...rosoft.com,
	tom@...pey.com,
	bharathsm@...rosoft.com,
	piastry@...rsoft.ru,
	samba-technical@...ts.samba.org,
	linux-kernel@...r.kernel.org
Cc: Ding Hui <dinghui@...gfor.com.cn>
Subject: [PATCH] cifs: fix an OOB issue in cifsConvertToUTF16()

The OOB can be triggered by making symlink in reparse=native mode.

Limit the srclen can not greater than maxlen.

Fixes: 2503a0dba989 ("CIFS: Add SMB2 support for is_path_accessible")
Signed-off-by: Ding Hui <dinghui@...gfor.com.cn>
---
 fs/smb/client/cifs_unicode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/smb/client/cifs_unicode.c b/fs/smb/client/cifs_unicode.c
index 4cc6e0896fad..cee43e71fa87 100644
--- a/fs/smb/client/cifs_unicode.c
+++ b/fs/smb/client/cifs_unicode.c
@@ -636,7 +636,7 @@ cifs_strndup_to_utf16(const char *src, const int maxlen, int *utf16_len,
 		*utf16_len = 0;
 		return NULL;
 	}
-	cifsConvertToUTF16(dst, src, strlen(src), cp, remap);
+	cifsConvertToUTF16(dst, src, strnlen(src, maxlen), cp, remap);
 	*utf16_len = len;
 	return dst;
 }
-- 
2.17.1