Re: [PATCH][next] net/tls: fix sign extension issue when left shifting u16 value

[Tariq Toukan]

On 6/30/2020 5:27 PM, Colin King wrote:
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> Left shifting the u16 value promotes it to a int and then it
> gets sign extended to a u64.  If len << 16 is greater than 0x7fffffff
> then the upper bits get set to 1 because of the implicit sign extension.
> Fix this by casting len to u64 before shifting it.
>
> Addresses-Coverity: ("integer handling issues")
> Fixes: ed9b7646b06a ("net/tls: Add asynchronous resync")
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> ---
>   include/net/tls.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/net/tls.h b/include/net/tls.h
> index c875c0a445a6..e5dac7e74e79 100644
> --- a/include/net/tls.h
> +++ b/include/net/tls.h
> @@ -637,7 +637,7 @@ tls_offload_rx_resync_async_request_start(struct sock *sk, __be32 seq, u16 len)
>   	struct tls_offload_context_rx *rx_ctx = tls_offload_ctx_rx(tls_ctx);
>   
>   	atomic64_set(&rx_ctx->resync_async->req, ((u64)ntohl(seq) << 32) |
> -		     (len << 16) | RESYNC_REQ | RESYNC_REQ_ASYNC);
> +		     ((u64)len << 16) | RESYNC_REQ | RESYNC_REQ_ASYNC);
>   	rx_ctx->resync_async->loglen = 0;
>   }
>   

Reviewed-by: Tariq Toukan <tariqt@xxxxxxxxxxxx>
Thanks!