From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793209674; b=D8iODOBK7efdoFCU2QUypEvIZ+KcGXKboXWD3zMlbLM+2zF1lKEE7l9s5GdNf6eSSUHF 9tCBJuWuTw7ApfeemO/qh+tcAa66JxswxtosaofmHuEAW5l+6F4GUem0BS5b6s/5iTq7t cUig8Vsi/U/lSCjNdXdAm5vf8gpsrcKzpnFgLFDFjjfGKBWNOlfIA/D3/gcqRvacHsRfR 4DqCq/NVw3MXz0Jc3W6V0/o3XJO7EvzY4aTzJxp6eK954iXw07vLXFByFHd/cHzoVNavS KxQqhn1uRYIl5/A+Bh561rTqfYwEuHEdvsSshW/0YVZQFUfW0wuxBGttFWd2BmMHQIg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793209674; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=CLXBRHKRFUoRDXCELXt61yjy/3DEV8BLSJMS7CCaFSk=; b=Uh6YWNQ1AGR3HHBobvCvmlMVZpowwRHxiHmOVUGAiQoBrIMor73fGu1fPmHoztNILu7d lekzkmE6rvEed28xmnkSa155Yzm6XKzmvWWDvsT0JZm1OWZVlRBxAwv7PYXxM/1eMW4MK KRpfbj6m0qL2k6PoB49hqPPtTAHMcfAqy/72RDzTUmio8OX/ZnGMDcDM/i7LhiPHaEPD1 NPAfWnkOJFjcxSBmbO7wzrNo7WVsyMdkBpDmHCo1ceSi8i3/hK00IUtc3BTg7LHgUAJng xTpuaUL2naS5UZst2NjnpbU8PSuaXIZZY7aY70zFSSusQiF9Ts8UmVdU8xa3YvjfoBQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=dUwbZ68N; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 70023606A31E; Wed, 28 Oct 2026 17:47:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=dUwbZ68N Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7500E1F01825; Wed, 28 Oct 2026 17:47:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793209674; bh=CLXBRHKRFUoRDXCELXt61yjy/3DEV8BLSJMS7CCaFSk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dUwbZ68N2tLoelYolK6TZGzAfNZAzaCwzT6Z3wYKDx8mgKVaxU2rAqhRvGi2tMp4F O6/LlU1EZzO8mFEgpAzAcPJMUmS3JjuWmZytAmoCEHTtkm7LE+B2Kl+LeHzzz3Vrvq mGSHiUrKYYSpTvuiHsJBrZEuAAb2T7jga9O6PD2U= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Carlier , Steven Rostedt Subject: [PATCH 6.18 036/109] tracing: Hold trace_types_lock when resetting last boot data from readers Date: Wed, 28 Oct 2026 18:00:20 +0100 Message-ID: <20261028165943.211524598@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165942.357251485@linuxfoundation.org> References: <20261028165942.357251485@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Carlier commit 5a6bd62f09147b49b31fd19d4eba122cb5f941a1 upstream. update_last_data_if_empty() is called from tracing_open() with O_TRUNC, tracing_read_pipe() and tracing_buffers_read() without trace_types_lock. Two readers can both pass the LAST_BOOT test and free module_delta twice, and a module notifier can update module_delta while it is being freed. Take trace_types_lock in those paths and keep the callers that already hold it on an unlocked variant. Cc: stable@vger.kernel.org Fixes: 32dc0042528d ("tracing: Reset last-boot buffers when reading out all cpu buffers") Link: https://patch.msgid.link/20261016061638.214847-2-devnexen@gmail.com Signed-off-by: David Carlier Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4847,6 +4847,7 @@ static int tracing_single_release_tr(str return single_release(inode, file); } +static bool __update_last_data_if_empty(struct trace_array *tr); static bool update_last_data_if_empty(struct trace_array *tr); static int tracing_open(struct inode *inode, struct file *file) @@ -5916,7 +5917,7 @@ tracing_set_trace_read(struct file *filp int tracer_init(struct tracer *t, struct trace_array *tr) { tracing_reset_online_cpus(&tr->array_buffer); - update_last_data_if_empty(tr); + __update_last_data_if_empty(tr); return t->init(tr); } @@ -6654,8 +6655,10 @@ static int tracing_wait_pipe(struct file return 1; } -static bool update_last_data_if_empty(struct trace_array *tr) +static bool __update_last_data_if_empty(struct trace_array *tr) { + lockdep_assert_held(&trace_types_lock); + if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) return false; @@ -6670,6 +6673,16 @@ static bool update_last_data_if_empty(st return true; } +static bool update_last_data_if_empty(struct trace_array *tr) +{ + /* Avoid the lock on the read path unless this is a last boot buffer */ + if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) + return false; + + guard(mutex)(&trace_types_lock); + return __update_last_data_if_empty(tr); +} + /* * Consumer reader. */ @@ -7599,7 +7612,7 @@ int tracing_set_clock(struct trace_array ring_buffer_set_clock(tr->max_buffer.buffer, trace_clocks[i].func); tracing_reset_online_cpus(&tr->max_buffer); #endif - update_last_data_if_empty(tr); + __update_last_data_if_empty(tr); if (tr->scratch && !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) { struct trace_scratch *tscratch = tr->scratch;