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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0A91C38142 for ; Tue, 24 Jan 2023 13:46:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234638AbjAXNqd (ORCPT ); Tue, 24 Jan 2023 08:46:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234618AbjAXNpn (ORCPT ); Tue, 24 Jan 2023 08:45:43 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DFA0247EE6; Tue, 24 Jan 2023 05:44:01 -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 ams.source.kernel.org (Postfix) with ESMTPS id 82764B811DA; Tue, 24 Jan 2023 13:43:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A8D0C4339C; Tue, 24 Jan 2023 13:43:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674567829; bh=uCIiHQzpCzLj7w5EfDpGVIqc92qbFsqM5jiyi3oFMOY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DUCwpsA2+uYyyJqGPuIgqHRh2qbOh7Bw8xhNeFE9iCT87exvN5wmUoRoHJEu1u27O ybybUNnxJAUnYJJObTZMl5NaPI/+mNJD6bsAJtl0x3lSghoe7qONVJXIPBvwaqv8L4 DOZ8q4NosiVQtUCjKfEHFL6tJRIR1v4ERIPe1YH1wCt1s782Ku59sysoinJvORMk3x d+HdUpmBupPJYdDvvUwyaUoF3AFoSEJRyKPbO8JoNdynko7TuekAy4GOM7kMuXXX/S 1R3GtDC1Sp2gzA3N1oMsf7oBQofZH1zoEdSbwwNqauUVNornZubK1I3oiKg1JgrAFH xOwB8q5hIKXkA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Hao Sun , Daniel Borkmann , Stanislav Fomichev , Sasha Levin , song@kernel.org, ast@kernel.org, andrii@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, bpf@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 2/6] bpf: Skip task with pid=1 in send_signal_common() Date: Tue, 24 Jan 2023 08:43:40 -0500 Message-Id: <20230124134344.637846-2-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230124134344.637846-1-sashal@kernel.org> References: <20230124134344.637846-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hao Sun [ Upstream commit a3d81bc1eaef48e34dd0b9b48eefed9e02a06451 ] The following kernel panic can be triggered when a task with pid=1 attaches a prog that attempts to send killing signal to itself, also see [1] for more details: Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b CPU: 3 PID: 1 Comm: systemd Not tainted 6.1.0-09652-g59fe41b5255f #148 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x100/0x178 lib/dump_stack.c:106 panic+0x2c4/0x60f kernel/panic.c:275 do_exit.cold+0x63/0xe4 kernel/exit.c:789 do_group_exit+0xd4/0x2a0 kernel/exit.c:950 get_signal+0x2460/0x2600 kernel/signal.c:2858 arch_do_signal_or_restart+0x78/0x5d0 arch/x86/kernel/signal.c:306 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296 do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd So skip task with pid=1 in bpf_send_signal_common() to avoid the panic. [1] https://lore.kernel.org/bpf/20221222043507.33037-1-sunhao.th@gmail.com Signed-off-by: Hao Sun Signed-off-by: Daniel Borkmann Acked-by: Stanislav Fomichev Link: https://lore.kernel.org/bpf/20230106084838.12690-1-sunhao.th@gmail.com Signed-off-by: Sasha Levin --- kernel/trace/bpf_trace.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 4d9f81802911..1e1345cd21b4 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -649,6 +649,9 @@ BPF_CALL_1(bpf_send_signal, u32, sig) return -EPERM; if (unlikely(!nmi_uaccess_okay())) return -EPERM; + /* Task should not be pid=1 to avoid kernel panic. */ + if (unlikely(is_global_init(current))) + return -EPERM; if (irqs_disabled()) { /* Do an early check on signal validity. Otherwise, -- 2.39.0