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 972784A2A58 for ; Wed, 16 Sep 2026 22:46:44 +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=1789598813; cv=none; b=uMTalWM1MbsEGBhTw9GV/9KKIrQv61/Tca116ZQwUVljIirm0iJjPuxPXkMpRqu9fpNXODOWzZVDAOdZIWHz/AJ+7XeCsnx7dJc/t86ox3ijUR5d76g94EQVxWtlMhbIawlKi6SK+d6WRB1fa47csL5CgVJGQCUMfZLAVkbY3yI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789598813; c=relaxed/simple; bh=q/ONyTjg7HZXYhrEWB+lnbkajoNVd4eYlZJcoRgSMac=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=D8mKuUcXVrzr+AH63idKop8IhBjbqqMcQUSg0mk0Xj1l04tQpD7rwFefZM0081XDHjh1Ys/lbi5yKzy26cV89HHIj6axfdLzOw5aXZD9KGDy8mgmimK4jhSwTaHeW0Hmci9D0WMy5s8l0O9AEzV8MRT6RNUdTXIf6DlwWgMnm+I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dsNpuDm9; 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="dsNpuDm9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85A891F00893; Wed, 16 Sep 2026 22:46:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789598800; bh=dJX+VM3osdkdzkR4l62B88q+VDg+sRgZuFRzYdxWgLo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dsNpuDm9biw22jdeoIlqihWcpBixWCqWvF/iuiLtoi3pxrt55iBZ7HxxMELbgm1XB 6u0hB26YF1zjv9DbeRoCbUhxRSbqgBFcKHnirI76h6Ab7Ng4osIOQo+UfjHGL6BJ1n aU3D2TjDgVNeyCPADXRP+/ea+9JvULFLEoCcnIolg6iwhQA1dkMVOCsYvIZoiSJOBZ d24ErTvk7ev0FqrSlAqMsvmB0hYu/kIaTncc+fJpJfHihBNsNARziTFX53FJTPppva OgzG074Vu0WloElGmjnkDwo5BnhkytPYFglC/lGNv3quFrlV/lBinzwt5Vm6L+jJhj mv1Y9Z15FIUag== From: Sasha Levin To: stable@vger.kernel.org Cc: Donggeun Yoo , Sashiko AI , Steven Rostedt , Sasha Levin Subject: [PATCH 5.15.y] tracing: Undo the registration when enabling the histogram trigger fails Date: Wed, 16 Sep 2026 18:46:38 -0400 Message-ID: <20260916224638.3198228-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026091607-wriggly-finite-bb4f@gregkh> References: <2026091607-wriggly-finite-bb4f@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 [ adapted cleanup to 5.15’s older trigger callbacks and registration order. ] Signed-off-by: Sasha Levin --- kernel/trace/trace_events_hist.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 5ecc78916431d..2fa1bc786f2a8 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -5676,11 +5676,12 @@ 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; } @@ -5759,13 +5760,13 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops, } } - if (unregistered && test->ops->free) - test->ops->free(test->ops, test); - if (hist_data->enable_timestamps) { if (!hist_data->remove || unregistered) tracing_set_filter_buffering(file->tr, false); } + + if (unregistered && test->ops->free) + test->ops->free(test->ops, test); } static bool hist_file_check_refs(struct trace_event_file *file) @@ -5964,8 +5965,11 @@ static int event_hist_trigger_func(struct event_command *cmd_ops, goto out_unreg; enable: ret = hist_trigger_enable(trigger_data, file); - if (ret) - goto out_unreg; + if (ret) { + cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file); + /* The unregister frees trigger_data, skip out_free */ + goto out; + } se_name = trace_event_name(file->event_call); se = find_synth_event(se_name); -- 2.53.0