Re: [PATCH][V2] backlight: sky81452: insure while loop does not allow negative array indexing
From: Daniel Thompson <hidden>
Date: 2020-02-27 11:46:30
Also in:
dri-devel, kernel-janitors, lkml
On Wed, Feb 26, 2020 at 07:58:26PM +0000, Colin King wrote:
From: Colin Ian King <redacted>
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 <redacted>
---
V2: fix typo in commit subject lineIsn't the correct spelling "ensure"?
quoted hunk ↗ jump to hunk
--- 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]);
This look still looks buggy to me (so I'd second Walter's request to change it to a for loop). If the code genuinely does not contain a bug then it probably needs a prominent comment explaining why it is correct not to honour sources[0]! Daniel.