From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7F6C62236EB; Tue, 30 Sep 2025 15:08:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759244932; cv=none; b=OgjqjpaUyhG4W3to7DEtYCt8qS7X2mOxfCOeHNwfctblgqZc99jMw8Wq5R9NYA85eZbvYlt89f5nauZ0iXAPow93E6MbsNf/BtWVAhTa/Y2zr554GwxQTj6gj8nDQrjX4nvIqa20ijHLBzSxWYenC6lkU7vn/e4zUlXn/pSxAF4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759244932; c=relaxed/simple; bh=er4b4xTgYtvpnT7Otc/yaPeuppluckEU9kfQBek9jok=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DrORgI/gtokGZapmcDH5tmgrxdwo2SzhCebH4/gYzP3BbfptMdVlNqDQybqtLk99xcpoFFhPJ3LDRwOG4j333TwVVvESEqnCDQB4x//sTrOktXVwEfL+YRpgKN6H1+dbrWkHbt0i6OtZIlxO8iVumtsaLcL6+XltiQaVZMbZIqw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CcR0XCm1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CcR0XCm1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE77AC4CEF0; Tue, 30 Sep 2025 15:08:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1759244932; bh=er4b4xTgYtvpnT7Otc/yaPeuppluckEU9kfQBek9jok=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CcR0XCm1Gzyfses4ecpBKDV7AoPLR3zk8lbitHTDdpIFOGfw3UodyRnhTiUJHipTD J5O6CSMa7rSvXmy13Bl3zucimhzA846onbYQdOvWFCOMh4Os/wAmFk56M/40nkCU2t +9ENUD7iC5tUZnb1TyRxP4IIr5cQlqlitQdwKb1s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Luo Gengkun , "Masami Hiramatsu (Google)" , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 5.15 014/151] tracing: Fix tracing_marker may trigger page fault during preempt_disable Date: Tue, 30 Sep 2025 16:45:44 +0200 Message-ID: <20250930143828.173404668@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250930143827.587035735@linuxfoundation.org> References: <20250930143827.587035735@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luo Gengkun [ Upstream commit 3d62ab32df065e4a7797204a918f6489ddb8a237 ] Both tracing_mark_write and tracing_mark_raw_write call __copy_from_user_inatomic during preempt_disable. But in some case, __copy_from_user_inatomic may trigger page fault, and will call schedule() subtly. And if a task is migrated to other cpu, the following warning will be trigger: if (RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer->committing))) An example can illustrate this issue: process flow CPU --------------------------------------------------------------------- tracing_mark_raw_write(): cpu:0 ... ring_buffer_lock_reserve(): cpu:0 ... cpu = raw_smp_processor_id() cpu:0 cpu_buffer = buffer->buffers[cpu] cpu:0 ... ... __copy_from_user_inatomic(): cpu:0 ... # page fault do_mem_abort(): cpu:0 ... # Call schedule schedule() cpu:0 ... # the task schedule to cpu1 __buffer_unlock_commit(): cpu:1 ... ring_buffer_unlock_commit(): cpu:1 ... cpu = raw_smp_processor_id() cpu:1 cpu_buffer = buffer->buffers[cpu] cpu:1 As shown above, the process will acquire cpuid twice and the return values are not the same. To fix this problem using copy_from_user_nofault instead of __copy_from_user_inatomic, as the former performs 'access_ok' before copying. Link: https://lore.kernel.org/20250819105152.2766363-1-luogengkun@huaweicloud.com Fixes: 656c7f0d2d2b ("tracing: Replace kmap with copy_from_user() in trace_marker writing") Signed-off-by: Luo Gengkun Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7af8bbc57531c..a6040a707abb7 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7233,7 +7233,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, entry = ring_buffer_event_data(event); entry->ip = _THIS_IP_; - len = __copy_from_user_inatomic(&entry->buf, ubuf, cnt); + len = copy_from_user_nofault(&entry->buf, ubuf, cnt); if (len) { memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE); cnt = FAULTED_SIZE; @@ -7308,7 +7308,7 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf, entry = ring_buffer_event_data(event); - len = __copy_from_user_inatomic(&entry->id, ubuf, cnt); + len = copy_from_user_nofault(&entry->id, ubuf, cnt); if (len) { entry->id = -1; memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE); -- 2.51.0