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

From: Colin Ian King <colin.king@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@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

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