On Mon, Jul 03, 2023 at 01:37:22PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> The overflow check in xdr_stream_decode_uint32_array() was added for
> 32-bit systems, but on 64-bit builds it causes a build warning when
> building with clang and W=1:
>
> In file included from init/do_mounts.c:22:
> include/linux/sunrpc/xdr.h:778:10: error: result of comparison of constant 4611686018427387903 with expression of type '__u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
> 778 | if (len > SIZE_MAX / sizeof(*p))
>
> Shut up the warning with a type cast.
>
> Fixes: 23a9dbbe0faf1 ("NFSD: prevent integer overflow on 32 bit systems")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> include/linux/sunrpc/xdr.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
> index f89ec4b5ea169..6736121ee6a03 100644
> --- a/include/linux/sunrpc/xdr.h
> +++ b/include/linux/sunrpc/xdr.h
> @@ -775,7 +775,7 @@ xdr_stream_decode_uint32_array(struct xdr_stream *xdr,
>
> if (unlikely(xdr_stream_decode_u32(xdr, &len) < 0))
> return -EBADMSG;
> - if (len > SIZE_MAX / sizeof(*p))
> + if ((size_t)len > SIZE_MAX / sizeof(*p))
> return -EBADMSG;
> p = xdr_inline_decode(xdr, len * sizeof(*p));
I sent a patch for this last week that takes a different approach.
https://lore.kernel.org/all/2390fdc8-13fa-4456-ab67-44f0744db412@moroto.mountain/
I probably should have used a Fixes tag just for informational purposes.
regards,
dan carpenter
