From mboxrd@z Thu Jan 1 00:00:00 1970 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 59949C433F5 for ; Fri, 7 Jan 2022 10:22:38 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4JVfRd07gMz3cSn for ; Fri, 7 Jan 2022 21:22:37 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=iogearbox.net (client-ip=213.133.104.62; helo=www62.your-server.de; envelope-from=daniel@iogearbox.net; receiver=) Received: from www62.your-server.de (www62.your-server.de [213.133.104.62]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4JVfR33PyJz3bY6 for ; Fri, 7 Jan 2022 21:22:07 +1100 (AEDT) Received: from sslproxy02.your-server.de ([78.47.166.47]) by www62.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92.3) (envelope-from ) id 1n5mNj-000D7w-Ok; Fri, 07 Jan 2022 11:21:59 +0100 Received: from [85.1.206.226] (helo=linux.home) by sslproxy02.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1n5mNj-000VjQ-EM; Fri, 07 Jan 2022 11:21:59 +0100 Subject: Re: [PATCH 01/13] bpf: Guard against accessing NULL pt_regs in bpf_get_task_stack() To: "Naveen N. Rao" , Michael Ellerman , Alexei Starovoitov References: From: Daniel Borkmann Message-ID: Date: Fri, 7 Jan 2022 11:21:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.103.3/26415/Fri Jan 7 10:26:59 2022) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ykaliuta@redhat.com, johan.almbladh@anyfinetworks.com, linuxppc-dev@lists.ozlabs.org, song@kernel.org, bpf@vger.kernel.org, Jiri Olsa , Hari Bathini Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 1/6/22 12:45 PM, Naveen N. Rao wrote: > task_pt_regs() can return NULL on powerpc for kernel threads. This is > then used in __bpf_get_stack() to check for user mode, resulting in a > kernel oops. Guard against this by checking return value of > task_pt_regs() before trying to obtain the call chain. > > Fixes: fa28dcb82a38f8 ("bpf: Introduce helper bpf_get_task_stack()") > Cc: stable@vger.kernel.org # v5.9+ > Signed-off-by: Naveen N. Rao Acked-by: Daniel Borkmann