AW: [PATCH][V2] backlight: sky81452: insure while loop does not allow negative array indexing

[Walter Harms]

hi all,
i would suggest converting this in to a more common for() loop.
Programmers are bad in counting backwards. that kind of bug is 
common.

re,
 wh
________________________________________
Von: kernel-janitors-owner at vger.kernel.org <kernel-janitors-owner at vger.kernel.org> im Auftrag von Colin King <colin.king at canonical.com>
Gesendet: Mittwoch, 26. Februar 2020 20:58
An: Lee Jones; Daniel Thompson; Jingoo Han; Bartlomiej Zolnierkiewicz; Gyungoh Yoo; Bryan Wu; dri-devel at lists.freedesktop.org; linux-fbdev at vger.kernel.org
Cc: kernel-janitors at vger.kernel.org; linux-kernel at vger.kernel.org
Betreff: [PATCH][V2] backlight: sky81452: insure while loop does not allow negative array indexing

From: Colin Ian King <colin.king at canonical.com>

In the unlikely event that num_entry is zero, the while loop
pre-decrements num_entry to cause negative array indexing into the
array sources. Fix this by iterating only if num_entry >= 0.

Addresses-Coverity: ("Out-of-bounds read")
Fixes: f705806c9f35 ("backlight: Add support Skyworks SKY81452 backlight driver")
Signed-off-by: Colin Ian King <colin.king at canonical.com>
---

V2: fix typo in commit subject line

---
 drivers/video/backlight/sky81452-backlight.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/backlight/sky81452-backlight.c b/drivers/video/backlight/sky81452-backlight.c
index 2355f00f5773..f456930ce78e 100644
--- a/drivers/video/backlight/sky81452-backlight.c
+++ b/drivers/video/backlight/sky81452-backlight.c
@@ -200,7 +200,7 @@ static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
                }

                pdata->enable = 0;
-               while (--num_entry)
+               while (--num_entry >= 0)
                        pdata->enable |= (1 << sources[num_entry]);
 
              int i;
                for(i=0;i<num_entry;i++)
                         pdata->enable |= (1 << sources[i]);

        }

--
2.25.0