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coresight: etb10: Fix possible NULL ptr dereference in etb_enable_perf() 

commit 22b2beaa7f upstream.

There was a report of NULL pointer dereference in ETF enable
path for perf CS mode with PID monitoring. It is almost 100%
reproducible when the process to monitor is something very
active such as chrome and with ETF as the sink, not ETR.

But code path shows that ETB has a similar path as ETF, so
there could be possible NULL pointer dereference crash in
ETB as well. Currently in a bid to find the pid, the owner
is dereferenced via task_pid_nr() call in etb_enable_perf()
and with owner being NULL, we can get a NULL pointer
dereference, so have a similar fix as ETF where we cache PID
in alloc_buffer() callback which is called as the part of
etm_setup_aux().

Fixes: 75d7dbd388 ("coresight: etb10: Add support for CPU-wide trace scenarios")
Cc: stable@vger.kernel.org
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20201127175256.1092685-11-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Sai Prakash Ranjan 2020-11-27 10:52:51 -07:00 committed by Greg Kroah-Hartman
parent 4c461e8d0e
commit 152631f027
1 changed files with 3 additions and 1 deletions
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4
drivers/hwtracing/coresight/coresight-etb10.c
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@ -176,6 +176,7 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data)
unsigned long flags;
struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
struct perf_output_handle *handle = data;
struct cs_buffers *buf = etm_perf_sink_config(handle);
spin_lock_irqsave(&drvdata->spinlock, flags);
@ -186,7 +187,7 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data)
}
/* Get a handle on the pid of the process to monitor */
pid = task_pid_nr(handle->event->owner);
pid = buf->pid;
if (drvdata->pid != -1 && drvdata->pid != pid) {
ret = -EBUSY;
@ -383,6 +384,7 @@ static void *etb_alloc_buffer(struct coresight_device *csdev,
if (!buf)
return NULL;
buf->pid = task_pid_nr(event->owner);
buf->snapshot = overwrite;
buf->nr_pages = nr_pages;
buf->data_pages = pages;