video: omap2: Use scnprintf() for avoiding potential buffer overflow

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 <tiwai@suse.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200311093230.24900-3-tiwai@suse.de

diff --git a/drivers/video/fbdev/omap2/omapfb/omapfb-sysfs.c b/drivers/video/fbdev/omap2/omapfb/omapfb-sysfs.c
index 4a5db17..2d39dbf 100644 (file)
--- a/drivers/video/fbdev/omap2/omapfb/omapfb-sysfs.c
+++ b/drivers/video/fbdev/omap2/omapfb/omapfb-sysfs.c
@@ -147,11 +147,11 @@ static ssize_t show_overlays(struct device *dev,
                        if (ovl == fbdev->overlays[ovlnum])
                                break;
 
-               l += snprintf(buf + l, PAGE_SIZE - l, "%s%d",
+               l += scnprintf(buf + l, PAGE_SIZE - l, "%s%d",
                                t == 0 ? "" : ",", ovlnum);
        }
 
-       l += snprintf(buf + l, PAGE_SIZE - l, "\n");
+       l += scnprintf(buf + l, PAGE_SIZE - l, "\n");
 
        omapfb_unlock(fbdev);
        unlock_fb_info(fbi);
@@ -328,11 +328,11 @@ static ssize_t show_overlays_rotate(struct device *dev,
        lock_fb_info(fbi);
 
        for (t = 0; t < ofbi->num_overlays; t++) {
-               l += snprintf(buf + l, PAGE_SIZE - l, "%s%d",
+               l += scnprintf(buf + l, PAGE_SIZE - l, "%s%d",
                                t == 0 ? "" : ",", ofbi->rotation[t]);
        }
 
-       l += snprintf(buf + l, PAGE_SIZE - l, "\n");
+       l += scnprintf(buf + l, PAGE_SIZE - l, "\n");
 
        unlock_fb_info(fbi);