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tracing: Fix race in trace_open and buffer resize call
commit bbeb97464eefc65f506084fd9f18f21653e01137 upstream.
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.
Link: https://lkml.kernel.org/r/1601976833-24377-1-git-send-email-gkohli@codeaurora.org
Cc: stable@vger.kernel.org
Fixes: 83f40318da
("ring-buffer: Make removal of ring buffer pages atomic")
Reported-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
c4a23c852e
commit
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@ -4448,6 +4448,8 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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return;
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/* prevent another thread from changing buffer sizes */
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mutex_lock(&buffer->mutex);
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atomic_inc(&buffer->resize_disabled);
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atomic_inc(&cpu_buffer->record_disabled);
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@ -4471,6 +4473,8 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
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atomic_dec(&cpu_buffer->record_disabled);
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atomic_dec(&buffer->resize_disabled);
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mutex_unlock(&buffer->mutex);
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}
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EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
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