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authorSai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>2020-11-27 20:52:51 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-11-27 22:23:13 +0300
commit22b2beaa7f166f550424cbb3b988aeaa7ef0425a (patch)
tree82b3f539a64913e6128238998f50d389ada3c225 /drivers/hwtracing
parent868663dd5d69fef05bfb004f91da5c30e9b93461 (diff)
downloadlinux-22b2beaa7f166f550424cbb3b988aeaa7ef0425a.tar.xz
coresight: etb10: Fix possible NULL ptr dereference in etb_enable_perf()
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.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hwtracing')
-rw-r--r--drivers/hwtracing/coresight/coresight-etb10.c4
1 files changed, 3 insertions, 1 deletions
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;