tracing: Add NULL checks for buffer in ring_buffer_free_read_page()

In a previous commit 7433632c9ff6, buffer, buffer->buffers and
buffer->buffers[cpu] in ring_buffer_wake_waiters() can be NULL,
and thus the related checks are added.

However, in the same call stack, these variables are also used in
ring_buffer_free_read_page():

tracing_buffers_release()
  ring_buffer_wake_waiters(iter->array_buffer->buffer)
    cpu_buffer = buffer->buffers[cpu] -> Add checks by previous commit
  ring_buffer_free_read_page(iter->array_buffer->buffer)
    cpu_buffer = buffer->buffers[cpu] -> No check

Thus, to avod possible null-pointer derefernces, the related checks
should be added.

These results are reported by a static tool designed by myself.

Link: https://lkml.kernel.org/r/[email protected]

Reported-by: TOTE Robot <[email protected]>
Signed-off-by: Jia-Ju Bai <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

0 files changed, 0 insertions, 0 deletions