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From:   Ruidong Tian <tianruidong@linux.alibaba.com>
To:     linux-kernel@vger.kernel.org
Cc:     tianruidong@linux.alibaba.com, alexander.shishkin@linux.intel.com,
        coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
        mike.leach@linaro.org, suzuki.poulose@arm.com, james.clark@arm.com
Subject: [PATCH v3 1/1] coresight: tmc: Explicit type conversions to prevent integer overflow
Date:   Fri,  4 Aug 2023 16:15:14 +0800
Message-Id: <20230804081514.120171-2-tianruidong@linux.alibaba.com>
In-Reply-To: <20230804081514.120171-1-tianruidong@linux.alibaba.com>
References: <20230714084349.31567-1-tianruidong@linux.alibaba.com>
 <20230804081514.120171-1-tianruidong@linux.alibaba.com>
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Perf cs_etm session executed unexpectedly when AUX buffer > 1G.

  perf record -C 0 -m ,2G -e cs_etm// -- <workload>
  [ perf record: Captured and wrote 2.615 MB perf.data ]

Perf only collect about 2M perf data rather than 2G. This is becasuse
the operation, "nr_pages << PAGE_SHIFT", in coresight tmc driver, will
overflow when nr_pages >= 0x80000(correspond to 1G AUX buffer). The
overflow cause buffer allocation to fail, and TMC driver will alloc
minimal buffer size(1M). You can just get about 2M perf data(1M AUX
buffer + perf data header) at least.

Explicit convert nr_pages to 64 bit to avoid overflow.

Fixes: 22f429f19c41 ("coresight: etm-perf: Add support for ETR backend")
Signed-off-by: Ruidong Tian <tianruidong@linux.alibaba.com>
Reviewed-by: James Clark <james.clark@arm.com>
---
 drivers/hwtracing/coresight/coresight-tmc-etf.c | 2 +-
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 5 +++--
 drivers/hwtracing/coresight/coresight-tmc.h     | 2 +-
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 79d8c64eac49..7406b65e2cdd 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -452,7 +452,7 @@ static int tmc_set_etf_buffer(struct coresight_device *csdev,
 		return -EINVAL;
 
 	/* wrap head around to the amount of space we have */
-	head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);
+	head = handle->head & (((unsigned long)buf->nr_pages << PAGE_SHIFT) - 1);
 
 	/* find the page to write to */
 	buf->cur = head / PAGE_SIZE;
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 766325de0e29..66dc5f97a009 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -45,7 +45,8 @@ struct etr_perf_buffer {
 };
 
 /* Convert the perf index to an offset within the ETR buffer */
-#define PERF_IDX2OFF(idx, buf)	((idx) % ((buf)->nr_pages << PAGE_SHIFT))
+#define PERF_IDX2OFF(idx, buf)		\
+		((idx) % ((unsigned long)(buf)->nr_pages << PAGE_SHIFT))
 
 /* Lower limit for ETR hardware buffer */
 #define TMC_ETR_PERF_MIN_BUF_SIZE	SZ_1M
@@ -1267,7 +1268,7 @@ alloc_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event,
 	 * than the size requested via sysfs.
 	 */
 	if ((nr_pages << PAGE_SHIFT) > drvdata->size) {
-		etr_buf = tmc_alloc_etr_buf(drvdata, (nr_pages << PAGE_SHIFT),
+		etr_buf = tmc_alloc_etr_buf(drvdata, ((ssize_t)nr_pages << PAGE_SHIFT),
 					    0, node, NULL);
 		if (!IS_ERR(etr_buf))
 			goto done;
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index b97da39652d2..0ee48c5ba764 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -325,7 +325,7 @@ ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table,
 static inline unsigned long
 tmc_sg_table_buf_size(struct tmc_sg_table *sg_table)
 {
-	return sg_table->data_pages.nr_pages << PAGE_SHIFT;
+	return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT;
 }
 
 struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
-- 
2.33.1