2023-08-11 14:08:57

by Arnd Bergmann

Subject: [PATCH] backlight: lp855x: fix unintialized function return

From: Arnd Bergmann <[email protected]>

The function now returns an error code in some cases, but fails to initialize
it in others:

drivers/video/backlight/lp855x_bl.c:252:11: error: variable 'ret' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
else if (lp->mode == REGISTER_BASED)
^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/video/backlight/lp855x_bl.c:256:9: note: uninitialized use occurs here
return ret;
^~~
drivers/video/backlight/lp855x_bl.c:252:7: note: remove the 'if' if its condition is always true
else if (lp->mode == REGISTER_BASED)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Since this case should not actually happen, return the -EINVAL code.

Fixes: 5145531be5fba ("backlight: lp855x: Catch errors when changing brightness")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/video/backlight/lp855x_bl.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
index 61a7f45bfad84..ea4fa69e49a70 100644
--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -252,6 +252,8 @@ static int lp855x_bl_update_status(struct backlight_device *bl)
else if (lp->mode == REGISTER_BASED)
ret = lp855x_write_byte(lp, lp->cfg->reg_brightness,
(u8)brightness);
+ else
+ ret = -EINVAL;

return ret;
}
--
2.39.2

2023-08-14 10:44:50

by Daniel Thompson

Subject: Re: [PATCH] backlight: lp855x: fix unintialized function return

On Fri, Aug 11, 2023 at 03:15:53PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> The function now returns an error code in some cases, but fails to initialize
> it in others:
>
> drivers/video/backlight/lp855x_bl.c:252:11: error: variable 'ret' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
> else if (lp->mode == REGISTER_BASED)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/video/backlight/lp855x_bl.c:256:9: note: uninitialized use occurs here
> return ret;
> ^~~
> drivers/video/backlight/lp855x_bl.c:252:7: note: remove the 'if' if its condition is always true
> else if (lp->mode == REGISTER_BASED)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Since this case should not actually happen, return the -EINVAL code.
>
> Fixes: 5145531be5fba ("backlight: lp855x: Catch errors when changing brightness")
> Signed-off-by: Arnd Bergmann <[email protected]>

I think we already received a patch for this:
https://lore.kernel.org/lkml/[email protected]/T/


Daniel.