From patchwork Wed Feb 1 17:31:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 13124805 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE03CC636CD for ; Wed, 1 Feb 2023 17:37:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231646AbjBARhN (ORCPT ); Wed, 1 Feb 2023 12:37:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232059AbjBARhF (ORCPT ); Wed, 1 Feb 2023 12:37:05 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 856157D9A5 for ; Wed, 1 Feb 2023 09:35:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675272948; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FDN2oUrxfhWHvX9N/vDCnLvcS04hB2Sskt8cijTVb7A=; b=MF8BwNDNlXgpuRPwn/8/0e8dN+AnGz3B47WV7n5c2Itc8BPPXo2f+xvoMO1ocHyB2Zfebh mKsyDJBG0AHi0+p05XE0eIF5XASTYxPz1YMgenjbtVjR3kbHnTT+43hAmlHuERDq81uM6H wAFktCgZUmuRd6TDTRUqDGszj7RrMns= Received: from mimecast-mx02.redhat.com (mx3-rdu2.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-142-YLanIt3dNSGNVOsjeaxxww-1; Wed, 01 Feb 2023 12:31:57 -0500 X-MC-Unique: YLanIt3dNSGNVOsjeaxxww-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9337C281DE6D; Wed, 1 Feb 2023 17:31:56 +0000 (UTC) Received: from firesoul.localdomain (ovpn-208-9.brq.redhat.com [10.40.208.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4F4E62026D4B; Wed, 1 Feb 2023 17:31:56 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 5A889300005EE; Wed, 1 Feb 2023 18:31:55 +0100 (CET) Subject: [PATCH bpf-next V2 2/4] selftests/bpf: xdp_hw_metadata cleanup cause segfault From: Jesper Dangaard Brouer To: bpf@vger.kernel.org, Stanislav Fomichev Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, martin.lau@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, dsahern@gmail.com, willemb@google.com, void@manifault.com, kuba@kernel.org, xdp-hints@xdp-project.net Date: Wed, 01 Feb 2023 18:31:55 +0100 Message-ID: <167527271533.937063.5717065138099679142.stgit@firesoul> In-Reply-To: <167527267453.937063.6000918625343592629.stgit@firesoul> References: <167527267453.937063.6000918625343592629.stgit@firesoul> User-Agent: StGit/1.4 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Using xdp_hw_metadata I experince Segmentation fault after seeing "detaching bpf program....". On my system the segfault happened when accessing bpf_obj->skeleton in xdp_hw_metadata__destroy(bpf_obj) call. That doesn't make any sense as this memory have not been freed by program at this point in time. Prior to calling xdp_hw_metadata__destroy(bpf_obj) the function close_xsk() is called for each RX-queue xsk. The real bug lays in close_xsk() that unmap via munmap() the wrong memory pointer. The call xsk_umem__delete(xsk->umem) will free xsk->umem, thus the call to munmap(xsk->umem, UMEM_SIZE) will have unpredictable behavior. And man page explain subsequent references to these pages will generate SIGSEGV. Unmapping xsk->umem_area instead removes the segfault. Fixes: 297a3f124155 ("selftests/bpf: Simple program to dump XDP RX metadata") Signed-off-by: Jesper Dangaard Brouer --- tools/testing/selftests/bpf/xdp_hw_metadata.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c index 3823b1c499cc..438083e34cce 100644 --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c @@ -121,7 +121,7 @@ static void close_xsk(struct xsk *xsk) xsk_umem__delete(xsk->umem); if (xsk->socket) xsk_socket__delete(xsk->socket); - munmap(xsk->umem, UMEM_SIZE); + munmap(xsk->umem_area, UMEM_SIZE); } static void refill_rx(struct xsk *xsk, __u64 addr)