linux-kernel - [PATCH RFC 1/4] coresight: tmc: check dump buffer is overflow

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Date:   Tue, 11 Apr 2017 17:10:26 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>, Mike Leach <mike.leach@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH RFC 1/4] coresight: tmc: check dump buffer is overflow

In the code dumping ETB buffer is terminated when read back value
0xFFFF_FFFF. This is not safe and introduce infinite looping for some
cases, e.g. when reset the CPU and read out ETB RAM.

Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Mike Leach <mike.leach@...aro.org>
Cc: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 drivers/hwtracing/coresight/coresight-tmc-etf.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 3a1c181..6150dac 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -54,6 +54,13 @@ static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
 			read_data = readl_relaxed(drvdata->base + TMC_RRD);
 			if (read_data == 0xFFFFFFFF)
 				return;
+
+			/* Check if allocated buffer is overflow */
+			if (drvdata->len >= drvdata->size) {
+				dev_info(drvdata->dev, "TMC dump overflow!\n");
+				return;
+			}
+
 			memcpy(bufp, &read_data, 4);
 			bufp += 4;
 			drvdata->len += 4;
-- 
2.7.4