tracing: Fix possible double free on failure of allocating trace buffer

commit 4397f04575c44e1440ec2e49b6302785c95fd2f8 upstream.

Jing Xia and Chunyan Zhang reported that on failing to allocate part of the
tracing buffer, memory is freed, but the pointers that point to them are not
initialized back to NULL, and later paths may try to free the freed memory
again. Jing and Chunyan fixed one of the locations that does this, but
missed a spot.

Link: http://lkml.kernel.org/r/20171226071253.8968-1-chunyan.zhang@spreadtrum.com
Fixes: 737223fbca3b1 ("tracing: Consolidate buffer allocation code")
Reported-by: Jing Xia <jing.xia@spreadtrum.com>
Reported-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 80ca62788772729808e7924c2ea12b40ce77fe18..b0452eefc2150cef65f88d87e4419763e71387ea 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6531,6 +6531,7 @@ allocate_trace_buffer(struct trace_array *tr, struct trace_buffer *buf, int size
        buf->data = alloc_percpu(struct trace_array_cpu);
        if (!buf->data) {
                ring_buffer_free(buf->buffer);
+               buf->buffer = NULL;
                return -ENOMEM;
        }