From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 45EA74DAF8E for ; Wed, 16 Sep 2026 18:36:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789583837; cv=none; b=SYSakatqy2r4hCKKxmXOxF38HPDGBd80bwDM+ovN6/iOoyehYlEdnCrH5aqWf0zy2JIA32PskcVRfQV5C7aT8l8Zt5cPoHtxJvN3mgtMYJP8YnjdGbv10schX6BWC72kk0TC2DX2Uxxkn9LU8tWBVkj+NLFrsfq07Ur6t5wu184= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789583837; c=relaxed/simple; bh=cF2gtn/+5gsF2X08XjiK1DF8+KJM3b7uPg9cJzZ056Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MEtzI6n3Vavjjj9Dz/URLUFPMRumm0OIeYyQWg+KJRR/xvHm2cEg/6eXPwBq8fqyDlAS++74a3leUytPnIAEKqOZHaX92PHUnAoNSD0bjMPRymi6b2QncNA7sFtIZPb+tt/txXXNHPBYQohkiDdaLoouzzAjd5dwjWUyjSxsKNs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Gwqvoo0D; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Gwqvoo0D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 462431F0089D; Wed, 16 Sep 2026 18:36:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789583801; bh=9DO7Jygc/jipm1ivz1OgMl8jsLQnqKsXyd6OZy5a12A=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Gwqvoo0D7LeDdjOqzW2+4ihWkiW2Y1aOSyJPNAJ4cjwBNZluWshv/onsRsHnzQb72 RjL9MD4cDY5wLxaXli50k3cL/2V/hClXeiBdYTAl0NWDdEH6CWVe2YP36VAOAwER9k 5SrsoAQt4LtSgwX+C/S1O9xvw9YOVUaIuR9ZlKJr6ncU8WaCS7GtgSQgfoxJbuSDDM T67IguMN3ABYLxA9jg9PllWiWw3K/E5RhSODAI5zNUfGqQlerYzdlXSmmsgRrF7mVj EsXG4hsJte+e/TEiXIXJygzdvKGUePi9T6AhdIsmLpFwdYLjYQo9kZ/zt7/qnio8wX fpxDfYvsBHDvw== From: Sasha Levin To: stable@vger.kernel.org Cc: Donggeun Yoo , Sashiko AI , Steven Rostedt , Sasha Levin Subject: [PATCH 6.18.y 3/3] tracing: Undo the registration when enabling the histogram trigger fails Date: Wed, 16 Sep 2026 14:36:37 -0400 Message-ID: <20260916183637.1770699-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260916183637.1770699-1-sashal@kernel.org> References: <2026091657-justly-crank-ffed@gregkh> <20260916183637.1770699-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Donggeun Yoo [ Upstream commit 92383cef66791a0c63a2f27755cadbdb2fbf270b ] Commit 6f86bdeab633 ("tracing: Fix bad hist from corrupting named_triggers list") described how a trigger that is registered but not on file->triggers ends up freed while still on the global named_triggers list, and moved the registration down so that hist_trigger_enable() follows it immediately. One path still gets there. hist_trigger_enable() adds the trigger and takes it straight back out when the event cannot be enabled: list_add_tail_rcu(&data->list, &file->triggers); update_cond_flag(file); if (trace_event_trigger_enable_disable(file, 1) < 0) { list_del_rcu(&data->list); update_cond_flag(file); ret--; } so the list walk in hist_unregister_trigger() matches nothing, test stays NULL, and the ->free() that would call del_named_trigger() is skipped. out_unreg falls through to out_free, which frees the trigger anyway: BUG: KASAN: slab-use-after-free in find_named_trigger+0xac/0xc0 Read of size 8 at addr ffff8880091d3160 by task init/1 find_named_trigger+0xac/0xc0 hist_register_trigger+0xc1/0xa00 event_hist_trigger_parse+0x3146/0x6af0 event_trigger_write+0xce/0x160 Freed by task 69: kfree+0x154/0x420 trigger_kthread_fn+0xfd/0x160 Leave the trigger where hist_unregister_trigger() can find it and let that undo the registration, which is the only code that knows all of what cmd_ops->init() took: the named list entry, the hist_pad reference, the reference on the trigger a named histogram is shared with, and the copied cmd_ops. It also pairs the failed trace_event_trigger_enable_disable(), whose sm_ref and buffered event reference are otherwise left behind. Since ->free() releases trigger_data and, for a trigger that does not share its histogram, hist_data with it, out_unreg can no longer fall through to out_free. For a trigger that does share, hist_register_trigger() has already destroyed the caller's hist_data, so the fall-through was reading freed memory there as well. Move the enable_timestamps check in hist_unregister_trigger() above the ->free() call for the same reason: hist_data does not outlive it once the trigger being removed is the one that owns it. Cc: stable@vger.kernel.org Fixes: 067fe038e70f ("tracing: Add variable reference handling to hist triggers") Reported-by: Sashiko AI Closes: https://lore.kernel.org/linux-trace-kernel/20260907092944.3950E1F00A3D@smtp.kernel.org/ Link: https://patch.msgid.link/20260907124420.607097-3-donggeunyoo.kernel@gmail.com Signed-off-by: Donggeun Yoo Signed-off-by: Steven Rostedt Signed-off-by: Sasha Levin --- kernel/trace/trace_events_hist.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index aa7736dcbb545..2288f63fbf56f 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -6632,11 +6632,12 @@ static int hist_trigger_enable(struct event_trigger_data *data, update_cond_flag(file); - if (trace_event_trigger_enable_disable(file, 1) < 0) { - list_del_rcu(&data->list); - update_cond_flag(file); + /* + * On failure the caller undoes the registration, and + * hist_unregister_trigger() can only find the trigger here. + */ + if (trace_event_trigger_enable_disable(file, 1) < 0) ret--; - } return ret; } @@ -6714,13 +6715,13 @@ static void hist_unregister_trigger(char *glob, } } - if (test && test->cmd_ops->free) - test->cmd_ops->free(test); - if (hist_data->enable_timestamps) { if (!hist_data->remove || test) tracing_set_filter_buffering(file->tr, false); } + + if (test && test->cmd_ops->free) + test->cmd_ops->free(test); } static bool hist_file_check_refs(struct trace_event_file *file) @@ -6925,6 +6926,8 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops, return ret; out_unreg: event_trigger_unregister(cmd_ops, file, glob+1, trigger_data); + /* The unregister frees trigger_data, skip out_free */ + goto out; out_free: event_trigger_reset_filter(cmd_ops, trigger_data); -- 2.53.0