From patchwork Mon Jan 31 10:55:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 538881 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 E9479C4332F for ; Mon, 31 Jan 2022 11:04:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359280AbiAaLEy (ORCPT ); Mon, 31 Jan 2022 06:04:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43136 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358325AbiAaLDn (ORCPT ); Mon, 31 Jan 2022 06:03:43 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86F37C06173E; Mon, 31 Jan 2022 03:03:05 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 249AA604F5; Mon, 31 Jan 2022 11:03:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED652C340E8; Mon, 31 Jan 2022 11:03:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643626984; bh=6eerhe6GybZvHheLPKe41Qbtj3MPhuJL4PFcSgB4LXA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2jd52qGaPbJLm8q6z+l7rvBtO7NAG9xL9whBdgxmtviehfFlDVHG2b28jeBfICuwz jCxFS+Y4gu28OLgViSnah9rJuCQH3+us4Js6MJx/OD/SRoInbE9nfNZ0eFdZfMAIah Ew0/iwnvZ+4fSbu9ebSl/TWqQH62/Ut+6IaofjLk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Naveen N. Rao" , Daniel Borkmann , Michael Ellerman Subject: [PATCH 5.10 007/100] bpf: Guard against accessing NULL pt_regs in bpf_get_task_stack() Date: Mon, 31 Jan 2022 11:55:28 +0100 Message-Id: <20220131105220.683243480@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220131105220.424085452@linuxfoundation.org> References: <20220131105220.424085452@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Naveen N. Rao commit b992f01e66150fc5e90be4a96f5eb8e634c8249e upstream. 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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/d5ef83c361cc255494afd15ff1b4fb02a36e1dcf.1641468127.git.naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/stackmap.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -664,13 +664,14 @@ BPF_CALL_4(bpf_get_task_stack, struct ta u32, size, u64, flags) { struct pt_regs *regs; - long res; + long res = -EINVAL; if (!try_get_task_stack(task)) return -EFAULT; regs = task_pt_regs(task); - res = __bpf_get_stack(regs, task, NULL, buf, size, flags); + if (regs) + res = __bpf_get_stack(regs, task, NULL, buf, size, flags); put_task_stack(task); return res;