From: Gaurav Kohli <gkohli@codeaurora.org>
To: rostedt@goodmis.org
Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
Gaurav Kohli <gkohli@codeaurora.org>,
stable@vger.kernel.org
Subject: [PATCH v1] trace: Fix race in trace_open and buffer resize call
Date: Tue, 6 Oct 2020 15:03:53 +0530 [thread overview]
Message-ID: <1601976833-24377-1-git-send-email-gkohli@codeaurora.org> (raw)
Below race can come, if trace_open and resize of
cpu buffer is running parallely on different cpus
CPUX CPUY
ring_buffer_resize
atomic_read(&buffer->resize_disabled)
tracing_open
tracing_reset_online_cpus
ring_buffer_reset_cpu
rb_reset_cpu
rb_update_pages
remove/insert pages
resetting pointer
This race can cause data abort or some times infinte loop in
rb_remove_pages and rb_insert_pages while checking pages
for sanity.
Take buffer lock to fix this.
Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>
Cc: stable@vger.kernel.org
---
Changes since v0:
-Addressed Steven's review comments.
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 93ef0ab..15bf28b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4866,6 +4866,9 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return;
+ /* prevent another thread from changing buffer sizes */
+ mutex_lock(&buffer->mutex);
+
atomic_inc(&cpu_buffer->resize_disabled);
atomic_inc(&cpu_buffer->record_disabled);
@@ -4876,6 +4879,8 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
atomic_dec(&cpu_buffer->record_disabled);
atomic_dec(&cpu_buffer->resize_disabled);
+
+ mutex_unlock(&buffer->mutex);
}
EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
@@ -4889,6 +4894,9 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
struct ring_buffer_per_cpu *cpu_buffer;
int cpu;
+ /* prevent another thread from changing buffer sizes */
+ mutex_lock(&buffer->mutex);
+
for_each_online_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
@@ -4907,6 +4915,8 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
atomic_dec(&cpu_buffer->record_disabled);
atomic_dec(&cpu_buffer->resize_disabled);
}
+
+ mutex_unlock(&buffer->mutex);
}
/**
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
next reply other threads:[~2020-10-06 9:34 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-06 9:33 Gaurav Kohli [this message]
2021-01-21 14:30 ` [PATCH v1] trace: Fix race in trace_open and buffer resize call Denis Efremov
2021-01-21 19:09 ` Steven Rostedt
2021-01-21 20:15 ` Denis Efremov
2021-01-21 20:37 ` Steven Rostedt
2021-01-22 10:59 ` Greg KH
2021-01-22 11:25 ` Gaurav Kohli
2021-01-22 14:37 ` Steven Rostedt
2021-01-23 10:49 ` Denis Efremov
2021-01-23 16:33 ` Gaurav Kohli
2021-01-24 3:21 ` Steven Rostedt
2021-01-24 9:57 ` Gaurav Kohli
2021-01-24 10:05 ` Greg KH
-- strict thread matches above, loose matches on Subject: below --
2020-09-24 13:55 Gaurav Kohli
2020-10-05 4:39 ` Gaurav Kohli
2020-10-05 14:25 ` Steven Rostedt
2020-10-05 14:27 ` Steven Rostedt
2020-10-05 16:29 ` Gaurav Kohli
2020-10-05 16:32 ` Steven Rostedt
2020-10-05 17:38 ` Gaurav Kohli
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