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 X-Spam-Level: X-Spam-Status: No, score=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8A83C4338F for ; Tue, 24 Aug 2021 17:11:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D6A7613D5 for ; Tue, 24 Aug 2021 17:11:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238636AbhHXRMm (ORCPT ); Tue, 24 Aug 2021 13:12:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:51264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240015AbhHXRJw (ORCPT ); Tue, 24 Aug 2021 13:09:52 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 27E5061884; Tue, 24 Aug 2021 17:00:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629824428; bh=02vaV8FE4gtUp3lc3K3rsU+IHWczu2FAe0Xwtf06Nsk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VxV4Ff2s4lgW7BiEygkCA91VKnHN3IGEf6xe6Yk96VslC+D1fFw+yH5z7ftWc6015 nGfOS2+0ogiAXN9BiXWnJOyDagKmhTvAT/JX69QlsYaeiS3pMcl5u6mGjXBpN/fKlx +QvshZmMPjtCVdKH+AAz65cFq0K6wEbCsrcN9ZxXF01Hyg9EtAARzieGyJre42er+b 7a2fYDxg2/PCvhuFQe4ztdt45oVwyce0GXF0/B9N5vdCPerOtn9j5pxys1s0XNeRhh 8ax9e+KtWgzzsMmGjU4U2NrsDFW+R5NIvNRDrHZONuA/YWV+EeK80kjiW2iXLDghOg ebQtzWcrYjMGw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Steven Rostedt (VMware)" , Masami Hiramatsu , Tom Zanussi , Sasha Levin Subject: [PATCH 5.10 79/98] tracing / histogram: Fix NULL pointer dereference on strcmp() on NULL event name Date: Tue, 24 Aug 2021 12:58:49 -0400 Message-Id: <20210824165908.709932-80-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210824165908.709932-1-sashal@kernel.org> References: <20210824165908.709932-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.10.61-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.10.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.10.61-rc1 X-KernelTest-Deadline: 2021-08-26T16:58+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" [ Upstream commit 5acce0bff2a0420ce87d4591daeb867f47d552c2 ] The following commands: # echo 'read_max u64 size;' > synthetic_events # echo 'hist:keys=common_pid:count=count:onmax($count).trace(read_max,count)' > events/syscalls/sys_enter_read/trigger Causes: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP CPU: 4 PID: 1763 Comm: bash Not tainted 5.14.0-rc2-test+ #155 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016 RIP: 0010:strcmp+0xc/0x20 Code: 75 f7 31 c0 0f b6 0c 06 88 0c 02 48 83 c0 01 84 c9 75 f1 4c 89 c0 c3 0f 1f 80 00 00 00 00 31 c0 eb 08 48 83 c0 01 84 d2 74 0f <0f> b6 14 07 3a 14 06 74 ef 19 c0 83 c8 01 c3 31 c0 c3 66 90 48 89 RSP: 0018:ffffb5fdc0963ca8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffffffffb3a4e040 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff9714c0d0b640 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00000022986b7cde R09: ffffffffb3a4dff8 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9714c50603c8 R13: 0000000000000000 R14: ffff97143fdf9e48 R15: ffff9714c01a2210 FS: 00007f1fa6785740(0000) GS:ffff9714da400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000002d863004 CR4: 00000000001706e0 Call Trace: __find_event_file+0x4e/0x80 action_create+0x6b7/0xeb0 ? kstrdup+0x44/0x60 event_hist_trigger_func+0x1a07/0x2130 trigger_process_regex+0xbd/0x110 event_trigger_write+0x71/0xd0 vfs_write+0xe9/0x310 ksys_write+0x68/0xe0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f1fa6879e87 The problem was the "trace(read_max,count)" where the "count" should be "$count" as "onmax()" only handles variables (although it really should be able to figure out that "count" is a field of sys_enter_read). But there's a path that does not find the variable and ends up passing a NULL for the event, which ends up getting passed to "strcmp()". Add a check for NULL to return and error on the command with: # cat error_log hist:syscalls:sys_enter_read: error: Couldn't create or find variable Command: hist:keys=common_pid:count=count:onmax($count).trace(read_max,count) ^ Link: https://lkml.kernel.org/r/20210808003011.4037f8d0@oasis.local.home Cc: Masami Hiramatsu Cc: stable@vger.kernel.org Fixes: 50450603ec9cb tracing: Add 'onmax' hist trigger action support Reviewed-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/trace/trace_events_hist.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 75529b311769..1b7f90e00eb0 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -3405,6 +3405,8 @@ trace_action_create_field_var(struct hist_trigger_data *hist_data, event = data->match_data.event; } + if (!event) + goto free; /* * At this point, we're looking at a field on another * event. Because we can't modify a hist trigger on -- 2.30.2