From: Sai Prakash Ranjan saiprakash.ranjan@codeaurora.org
stable inclusion from stable-5.10.3 commit 3e89c7f978890460bcbcfd74b03e524bd1d1348c bugzilla: 46871
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commit 22b2beaa7f166f550424cbb3b988aeaa7ef0425a 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: 75d7dbd38824 ("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.o... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
Signed-off-by: Chen Jun chenjun102@huawei.com --- drivers/hwtracing/coresight/coresight-etb10.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c index 248cc82c838e..1b320ab581ca 100644 --- a/drivers/hwtracing/coresight/coresight-etb10.c +++ b/drivers/hwtracing/coresight/coresight-etb10.c @@ -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;