[PATCH] [v2] net: hns3: fix hclge_dbg_dump_tm_pg() stack usage

* [PATCH] [v2] net: hns3: fix hclge_dbg_dump_tm_pg() stack usage
@ 2021-09-28  8:58 Arnd Bergmann
  2021-09-28 12:50 ` patchwork-bot+netdevbpf
  0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2021-09-28  8:58 UTC (permalink / raw)
  To: Yisen Zhuang, Salil Mehta, David S. Miller, Jakub Kicinski
  Cc: Arnd Bergmann, Guangbin Huang, Yufeng Mo, Jiaran Zhang,
	Jian Shen, netdev, linux-kernel

From: Arnd Bergmann <arnd@arndb.de>

This function copies strings around between multiple buffers
including a large on-stack array that causes a build warning
on 32-bit systems:

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c: In function 'hclge_dbg_dump_tm_pg':
drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c:782:1: error: the frame size of 1424 bytes is larger than 1400 bytes [-Werror=frame-larger-than=]

The function can probably be cleaned up a lot, to go back to
printing directly into the output buffer, but dynamically allocating
the structure is a simpler workaround for now.

Fixes: 04d96139ddb3 ("net: hns3: refine function hclge_dbg_dump_tm_pri()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
Changes in v2:
 - rearrange local variable as suggested by huangguangbin
---
 .../hisilicon/hns3/hns3pf/hclge_debugfs.c     | 28 ++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c
index 87d96f82c318..32f62cd2dd99 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c
@@ -719,9 +719,9 @@ static void hclge_dbg_fill_shaper_content(struct hclge_tm_shaper_para *para,
 	sprintf(result[(*index)++], "%6u", para->rate);
 }
 
-static int hclge_dbg_dump_tm_pg(struct hclge_dev *hdev, char *buf, int len)
+static int __hclge_dbg_dump_tm_pg(struct hclge_dev *hdev, char *data_str,
+				  char *buf, int len)
 {
-	char data_str[ARRAY_SIZE(tm_pg_items)][HCLGE_DBG_DATA_STR_LEN];
 	struct hclge_tm_shaper_para c_shaper_para, p_shaper_para;
 	char *result[ARRAY_SIZE(tm_pg_items)], *sch_mode_str;
 	u8 pg_id, sch_mode, weight, pri_bit_map, i, j;
@@ -729,8 +729,10 @@ static int hclge_dbg_dump_tm_pg(struct hclge_dev *hdev, char *buf, int len)
 	int pos = 0;
 	int ret;
 
-	for (i = 0; i < ARRAY_SIZE(tm_pg_items); i++)
-		result[i] = &data_str[i][0];
+	for (i = 0; i < ARRAY_SIZE(tm_pg_items); i++) {
+		result[i] = data_str;
+		data_str += HCLGE_DBG_DATA_STR_LEN;
+	}
 
 	hclge_dbg_fill_content(content, sizeof(content), tm_pg_items,
 			       NULL, ARRAY_SIZE(tm_pg_items));
@@ -781,6 +783,24 @@ static int hclge_dbg_dump_tm_pg(struct hclge_dev *hdev, char *buf, int len)
 	return 0;
 }
 
+static int hclge_dbg_dump_tm_pg(struct hclge_dev *hdev, char *buf, int len)
+{
+	char *data_str;
+	int ret;
+
+	data_str = kcalloc(ARRAY_SIZE(tm_pg_items),
+			   HCLGE_DBG_DATA_STR_LEN, GFP_KERNEL);
+
+	if (!data_str)
+		return -ENOMEM;
+
+	ret = __hclge_dbg_dump_tm_pg(hdev, data_str, buf, len);
+
+	kfree(data_str);
+
+	return ret;
+}
+
 static int hclge_dbg_dump_tm_port(struct hclge_dev *hdev,  char *buf, int len)
 {
 	struct hclge_tm_shaper_para shaper_para;
-- 
2.29.2


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