Hi Dan-
> On Mar 14, 2022, at 10:09 AM, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> On a 32 bit system, the "len * sizeof(*p)" operation can have an
> integer overflow.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> It's hard to pick a Fixes tag for this... The temptation is to say:
> Fixes: 37c88763def8 ("NFSv4; Clean up XDR encoding of type bitmap4")
> But there were integer overflows in the code before that as well.
>
> include/linux/sunrpc/xdr.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
> index b519609af1d0..61b92e6b9813 100644
> --- a/include/linux/sunrpc/xdr.h
> +++ b/include/linux/sunrpc/xdr.h
> @@ -731,6 +731,8 @@ xdr_stream_decode_uint32_array(struct xdr_stream *xdr,
>
> if (unlikely(xdr_stream_decode_u32(xdr, &len) < 0))
> return -EBADMSG;
> + if (len > ULONG_MAX / sizeof(*p))
> + return -EBADMSG;
IIUC xdr_inline_decode() returns NULL if the value of
"len * sizeof(p)" is larger than the remaining XDR buffer
size. I don't believe this extra check is necessary.
> p = xdr_inline_decode(xdr, len * sizeof(*p));
> if (unlikely(!p))
> return -EBADMSG;
> --
> 2.20.1
>
--
Chuck Lever
