From: Makar Semyonov Date: Thu, 4 Sep 2025 12:28:41 +0000 (+0300) Subject: cifs: prevent NULL pointer dereference in UTF16 conversion X-Git-Tag: v6.17-rc5~13^2 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=70bccd9855dae56942f2b18a08ba137bb54093a0;p=users%2Fgriffoul%2Flinux.git cifs: prevent NULL pointer dereference in UTF16 conversion There can be a NULL pointer dereference bug here. NULL is passed to __cifs_sfu_make_node without checks, which passes it unchecked to cifs_strndup_to_utf16, which in turn passes it to cifs_local_to_utf16_bytes where '*from' is dereferenced, causing a crash. This patch adds a check for NULL 'src' in cifs_strndup_to_utf16 and returns NULL early to prevent dereferencing NULL pointer. Found by Linux Verification Center (linuxtesting.org) with SVACE Signed-off-by: Makar Semyonov Cc: stable@vger.kernel.org Signed-off-by: Steve French --- diff --git a/fs/smb/client/cifs_unicode.c b/fs/smb/client/cifs_unicode.c index 4cc6e0896fad..f8659d36793f 100644 --- a/fs/smb/client/cifs_unicode.c +++ b/fs/smb/client/cifs_unicode.c @@ -629,6 +629,9 @@ cifs_strndup_to_utf16(const char *src, const int maxlen, int *utf16_len, int len; __le16 *dst; + if (!src) + return NULL; + len = cifs_local_to_utf16_bytes(src, maxlen, cp); len += 2; /* NULL */ dst = kmalloc(len, GFP_KERNEL);