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 81259432E6E; Thu, 30 Jul 2026 14:36:45 +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=1785422206; cv=none; b=RZ7V82iYkBR17vHIuxW5BfDoQmunxJ6CH7M/JA68XgMdrD5n5arP9yAnclbucfn/2tMEWPW5soXPkMLXTHEi7Iduxm9YnyveQH9oLcX5A20g6v1NSy09s9PS9232HatqKDPwGw9VgwPNau8FIpK4E5KJrLLWsfskF577m3tSgLU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785422206; c=relaxed/simple; bh=32m55Ru7fstbwgONuKx0AB6olQRgS2GQax7ragUJV8Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jJ+YA6JECHUWVeoFhqvt/gfjBTYc9IUiESYy/z5m814CC4XnIm6YzTGn6c8ZhiSMJDsRx0k6geJ+mAZr6iZ25aLZ4G1N5H02L/GbG/llBdPE1a1E6niPql8icWUeLonR9YoBV42hQAYT4BSE62BcxtQahHIJet90z3j49FdYnkQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2gYrkPhQ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2gYrkPhQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C81BD1F000E9; Thu, 30 Jul 2026 14:36:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785422205; bh=H7/nVeYaKP+bgIINK7N0iH58RtY+Wh7axr6g0Ab/1hw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2gYrkPhQUUyC84uHdo8y5oPf6IpIhkiVoIgbtF+HWeLduHNOffQe2WpKBEt30bO6q CuIeWM02aLdhC0DPFLEugfzHUu9R8WIQdT2d5wY16bpCw9XCrW+C501rZI82zNEq4e keSuPzjYsEL2zIUfTY72u3iQ8Y6nwkTcjo9CSzS0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Masami Hiramatsu (Google)" , Steven Rostedt , David Carlier , Sasha Levin Subject: [PATCH 7.1 358/744] tracing: Fix use-after-free freeing trigger private data Date: Thu, 30 Jul 2026 16:10:31 +0200 Message-ID: <20260730141451.893812703@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141444.267951807@linuxfoundation.org> References: <20260730141444.267951807@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Carlier [ Upstream commit 79097812153b826fc156a2930ec8a90ed9edf4a2 ] Commit 61d445af0a7c ("tracing: Add bulk garbage collection of freeing event_trigger_data") moved the kfree() of event_trigger_data to a kthread that runs tracepoint_synchronize_unregister() before freeing. That removed the synchronization the trigger .free callbacks used to get implicitly and inline from trigger_data_free(). event_hist_trigger_free(), event_hist_trigger_named_free() and event_enable_trigger_free() free their satellite data (hist_data, cmd_ops, enable_data) right after trigger_data_free() returns. With the synchronization now deferred to the kthread, a concurrent tracepoint handler can still reach that data through the list_del_rcu()'d trigger, causing a use-after-free. The histogram teardown must stay synchronous: remove_hist_vars() and unregister_field_var_hists() have to detach a synthetic event from the histogram before the trigger-removal write returns, otherwise a following command races in and the synthetic-event removal fails with -EBUSY, as the trigger-synthetic-eprobe.tc selftest catches. Make those callbacks wait with the correct barrier - tracepoint_synchronize_unregister(), matching the free kthread - before freeing. The enable trigger has no such synchronous requirement, and a blocking synchronize there would re-serialize the path that commit deliberately deferred. Give it an optional private_data_free() callback that the free kthread runs after its grace period, and free enable_data from there. Link: https://patch.msgid.link/20260724030523.19081-1-devnexen@gmail.com Suggested-by: Masami Hiramatsu (Google) Suggested-by: Steven Rostedt Fixes: 61d445af0a7c ("tracing: Add bulk garbage collection of freeing event_trigger_data") Signed-off-by: David Carlier Signed-off-by: Steven Rostedt Signed-off-by: Sasha Levin --- kernel/trace/trace.h | 1 + kernel/trace/trace_events_hist.c | 2 ++ kernel/trace/trace_events_trigger.c | 18 +++++++++++++++--- 3 files changed, 18 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 80fe152af1dd84..bf77331f56a4dd 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1941,6 +1941,7 @@ struct event_trigger_data { struct list_head named_list; struct event_trigger_data *named_data; struct llist_node llist; + void (*private_data_free)(struct event_trigger_data *data); }; /* Avoid typos */ diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 9701650c89b2f2..e287dad25fc39f 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -6358,6 +6358,7 @@ static void event_hist_trigger_free(struct event_trigger_data *data) trigger_data_free(data); + tracepoint_synchronize_unregister(); remove_hist_vars(hist_data); unregister_field_var_hists(hist_data); @@ -6397,6 +6398,7 @@ static void event_hist_trigger_named_free(struct event_trigger_data *data) del_named_trigger(data); trigger_data_free(data); + tracepoint_synchronize_unregister(); kfree(cmd_ops); } } diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index 655db2e8251349..46e60b70a4bbc4 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -38,6 +38,13 @@ static void trigger_create_kthread_locked(void) } } +static void trigger_data_free_one(struct event_trigger_data *data) +{ + if (data->private_data_free) + data->private_data_free(data); + kfree(data); +} + static void trigger_data_free_queued_locked(void) { struct event_trigger_data *data, *tmp; @@ -52,7 +59,7 @@ static void trigger_data_free_queued_locked(void) tracepoint_synchronize_unregister(); llist_for_each_entry_safe(data, tmp, llnodes, llist) - kfree(data); + trigger_data_free_one(data); } /* Bulk garbage collection of event_trigger_data elements */ @@ -75,7 +82,7 @@ static int trigger_kthread_fn(void *ignore) tracepoint_synchronize_unregister(); llist_for_each_entry_safe(data, tmp, llnodes, llist) - kfree(data); + trigger_data_free_one(data); } return 0; @@ -1717,6 +1724,11 @@ int event_enable_trigger_print(struct seq_file *m, return 0; } +static void enable_trigger_private_data_free(struct event_trigger_data *data) +{ + kfree(data->private_data); +} + void event_enable_trigger_free(struct event_trigger_data *data) { struct enable_trigger_data *enable_data = data->private_data; @@ -1728,9 +1740,9 @@ void event_enable_trigger_free(struct event_trigger_data *data) if (!data->ref) { /* Remove the SOFT_MODE flag */ trace_event_enable_disable(enable_data->file, 0, 1); + data->private_data_free = enable_trigger_private_data_free; trace_event_put_ref(enable_data->file->event_call); trigger_data_free(data); - kfree(enable_data); } } -- 2.53.0