On Tue, 2021-08-17 at 12:27 +0200, Len Baker wrote:
> strlcpy() reads the entire source buffer first. This read may exceed the
> destination size limit. This is both inefficient and can lead to linear
> read overflows if a source string is not NUL-terminated.
>
> Also, the strnlen() call does not avoid the read overflow in the strlcpy
> function when a not NUL-terminated string is passed.
>
> So, replace this block by a call to kstrndup() that avoids this type of
> overflow and does the same.
>
> Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions")
> Signed-off-by: Len Baker <len.baker@xxxxxxx>
> ---
> fs/cifs/cifs_unicode.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/fs/cifs/cifs_unicode.c b/fs/cifs/cifs_unicode.c
> index 9bd03a231032..171ad8b42107 100644
> --- a/fs/cifs/cifs_unicode.c
> +++ b/fs/cifs/cifs_unicode.c
> @@ -358,14 +358,9 @@ cifs_strndup_from_utf16(const char *src, const int maxlen,
> if (!dst)
> return NULL;
> cifs_from_utf16(dst, (__le16 *) src, len, maxlen, codepage,
> - NO_MAP_UNI_RSVD);
> + NO_MAP_UNI_RSVD);
> } else {
> - len = strnlen(src, maxlen);
> - len++;
> - dst = kmalloc(len, GFP_KERNEL);
> - if (!dst)
> - return NULL;
> - strlcpy(dst, src, len);
> + dst = kstrndup(src, maxlen, GFP_KERNEL);
> }
>
> return dst;
> --
> 2.25.1
>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
