From: Jing Xia <[email protected]>
Double free of the ring buffer happens when it fails to alloc new
ring buffer instance for max_buffer if TRACER_MAX_TRACE is configured.
The root cause is that the pointer is not set to NULL after the buffer
is freed in allocate_trace_buffers(), and the freeing of the ring
buffer is invoked again later if the pointer is not equal to Null,
as:
instance_mkdir()
|-allocate_trace_buffers()
|-allocate_trace_buffer(tr, &tr->trace_buffer...)
|-allocate_trace_buffer(tr, &tr->max_buffer...)
// allocate fail(-ENOMEM),first free
// and the buffer pointer is not set to null
|-ring_buffer_free(tr->trace_buffer.buffer)
// out_free_tr
|-free_trace_buffers()
|-free_trace_buffer(&tr->trace_buffer);
//if trace_buffer is not null, free again
|-ring_buffer_free(buf->buffer)
|-rb_free_cpu_buffer(buffer->buffers[cpu])
// ring_buffer_per_cpu is null, and
// crash in ring_buffer_per_cpu->pages
Link:
http://lkml.kernel.org/r/[email protected]
Cc: [email protected]
Fixes: 737223fbca3b1 ("tracing: Consolidate buffer allocation code")
Signed-off-by: Jing Xia <[email protected]>
Signed-off-by: Chunyan Zhang <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
---
kernel/trace/trace.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 73652d5318b2..0e53d46544b8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7603,7 +7603,9 @@ static int allocate_trace_buffers(struct trace_array *tr,
int size)
allocate_snapshot ? size : 1);
if (WARN_ON(ret)) {
ring_buffer_free(tr->trace_buffer.buffer);
+ tr->trace_buffer.buffer = NULL;
free_percpu(tr->trace_buffer.data);
+ tr->trace_buffer.data = NULL;
return -ENOMEM;
}
tr->allocated_snapshot = allocate_snapshot;
--
2.13.2
