# \[PATCH 3/3\] video: uvesafb: Use scnprintf() for avoiding potential buffer overflow

- From: Takashi Iwai \<hidden\>
- Date: 2020-03-11 09:32:30 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2020/03/13467021
- Thread: https://ratatoskr.run/linux-fbdev/2020/03/13467021/t.md

```text
Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <redacted>
---
 drivers/video/fbdev/uvesafb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/uvesafb.c b/drivers/video/fbdev/uvesafb.c
index 53d08d1b56f5..1b385cf76110 100644
--- a/drivers/video/fbdev/uvesafb.c
+++ b/drivers/video/fbdev/uvesafb.c
@@ -1560,7 +1560,7 @@ static ssize_t uvesafb_show_vbe_modes(struct device *dev,
 	int ret = 0, i;
 
 	for (i = 0; i < par->vbe_modes_cnt && ret < PAGE_SIZE; i++) {
-		ret += snprintf(buf + ret, PAGE_SIZE - ret,
+		ret += scnprintf(buf + ret, PAGE_SIZE - ret,
 			"%dx%d-%d, 0x%.4x\n",
 			par->vbe_modes[i].x_res, par->vbe_modes[i].y_res,
 			par->vbe_modes[i].depth, par->vbe_modes[i].mode_id);
-- 
2.16.4
```