From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 10F182E628 for ; Tue, 3 Oct 2023 16:59:21 +0000 (UTC) Received: from us-smtp-delivery-44.mimecast.com (unknown [207.211.30.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA762A6 for ; Tue, 3 Oct 2023 09:59:19 -0700 (PDT) Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-689-xuwW08IkPQyY_aY8uirDQw-1; Tue, 03 Oct 2023 12:59:02 -0400 X-MC-Unique: xuwW08IkPQyY_aY8uirDQw-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B175F3C1ACE5; Tue, 3 Oct 2023 16:58:44 +0000 (UTC) Received: from hog (unknown [10.45.224.63]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 70EB64A9B0C; Tue, 3 Oct 2023 16:58:42 +0000 (UTC) Date: Tue, 3 Oct 2023 18:58:40 +0200 From: Sabrina Dubroca To: "Gustavo A. R. Silva" Cc: Ayush Sawal , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rohit Maheshwari , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v2][next] cxgb4/ch_ktls: Fix undefined behavior bug in struct chcr_ktls_ofld_ctx_tx Message-ID: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Spam-Status: No, score=0.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_BLOCKED, RCVD_IN_VALIDITY_RPBL,RDNS_NONE,SPF_HELO_NONE,SPF_NONE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net 2023-10-03, 12:56:54 +0200, Gustavo A. R. Silva wrote: > `struct tls_offload_context_tx` is a flexible structure, which means > that it contains a flexible-array member at the bottom. This could > potentially lead to an overwrite of the objects following `base` in > `struct chcr_ktls_ofld_ctx_tx` at run-time. > > Notice that flexible-array member `driver_state` in `struct > tls_offload_context_tx` can grow up to 16 bytes: > > | include/net/tls.h-170: > | #define TLS_DRIVER_STATE_SIZE_TX 16 > > | include/net/tls.h-173: > | #define TLS_OFFLOAD_CONTEXT_SIZE_TX \ > | (sizeof(struct tls_offload_context_tx) + TLS_DRIVER_STATE_SIZE_TX) > > | net/tls/tls_device.c-1119: > | offload_ctx = kzalloc(TLS_OFFLOAD_CONTEXT_SIZE_TX, GFP_KERNEL); > > Fix this by placing the declaration of object `base` at the end of > `struct chcr_ktls_ofld_ctx_tx`. AFAIU, chcr_ktls_ofld_ctx_tx just misuses the extra space allocated by tls_set_device_offload. There's no bug, but the code is a bit confusing. I don't think this patch works, since chcr_ktls doesn't allocate its own memory for chcr_ktls_ofld_ctx_tx. As part of a series of cleanups that I'll submit soon (hopefully this week), I updated chcr_ktls to use the driver_state part of tls_offload_context_tx (instead of the cast in chcr_get_ktls_tx_context), and then removed the flexarrays from tls_offload_context_tx and tls_offload_context_rx (since they're actually a fixed size). -- Sabrina