* re: ALSA: control - add layer registration routines
@ 2021-03-31 15:17 Colin Ian King
2021-03-31 18:09 ` Jaroslav Kysela
0 siblings, 1 reply; 2+ messages in thread
From: Colin Ian King @ 2021-03-31 15:17 UTC (permalink / raw
To: Jaroslav Kysela
Cc: Takashi Iwai, Mark Brown, Takashi Sakamoto, alsa-devel,
linux-kernel@vger.kernel.org
Hi,
Static analysis on linux-next with Coverity has detected a potential
issue in the following commit:
commit 3f0638a0333bfdd0549985aa620f2ab69737af47
Author: Jaroslav Kysela <perex@perex.cz>
Date: Wed Mar 17 18:29:41 2021 +0100
ALSA: control - add layer registration routines
The static analysis is as follows:
2072 void snd_ctl_disconnect_layer(struct snd_ctl_layer_ops *lops)
2073 {
2074 struct snd_ctl_layer_ops *lops2, *prev_lops2;
2075
2076 down_write(&snd_ctl_layer_rwsem);
assignment: Assigning: prev_lops2 = NULL.
2077 for (lops2 = snd_ctl_layer, prev_lops2 = NULL; lops2; lops2
= lops2->next)
2078 if (lops2 == lops) {
null: At condition prev_lops2, the value of prev_lops2 must be NULL.
dead_error_condition: The condition !prev_lops2 must be true.
2079 if (!prev_lops2)
2080 snd_ctl_layer = lops->next;
2081 else
'Constant' variable guards dead code (DEADCODE) dead_error_line:
Execution cannot reach this statement: prev_lops2->next = lops->next;.
Local variable prev_lops2 is assigned only once, to a constant
value, making it effectively constant throughout its scope. If this is
not the intent, examine the logic to see if there is a missing
assignment that would make prev_lops2 not remain constant.
2082 prev_lops2->next = lops->next;
2083 break;
2084 }
2085 up_write(&snd_ctl_layer_rwsem);
2086 }
I couldn't quite figure out the original intent of the prev_lops use, so
I'd thought I'd report this issue as the code does look incorrect.
Colin
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: ALSA: control - add layer registration routines
2021-03-31 15:17 ALSA: control - add layer registration routines Colin Ian King
@ 2021-03-31 18:09 ` Jaroslav Kysela
0 siblings, 0 replies; 2+ messages in thread
From: Jaroslav Kysela @ 2021-03-31 18:09 UTC (permalink / raw
To: Colin Ian King
Cc: Takashi Iwai, Mark Brown, Takashi Sakamoto, alsa-devel,
linux-kernel@vger.kernel.org
Dne 31. 03. 21 v 17:17 Colin Ian King napsal(a):
> Hi,
>
> Static analysis on linux-next with Coverity has detected a potential
> issue in the following commit:
>
> commit 3f0638a0333bfdd0549985aa620f2ab69737af47
> Author: Jaroslav Kysela <perex@perex.cz>
> Date: Wed Mar 17 18:29:41 2021 +0100
>
> ALSA: control - add layer registration routines
>
> The static analysis is as follows:
>
> 2072 void snd_ctl_disconnect_layer(struct snd_ctl_layer_ops *lops)
> 2073 {
> 2074 struct snd_ctl_layer_ops *lops2, *prev_lops2;
> 2075
> 2076 down_write(&snd_ctl_layer_rwsem);
>
> assignment: Assigning: prev_lops2 = NULL.
>
> 2077 for (lops2 = snd_ctl_layer, prev_lops2 = NULL; lops2; lops2
> = lops2->next)
> 2078 if (lops2 == lops) {
>
> null: At condition prev_lops2, the value of prev_lops2 must be NULL.
> dead_error_condition: The condition !prev_lops2 must be true.
>
> 2079 if (!prev_lops2)
> 2080 snd_ctl_layer = lops->next;
> 2081 else
>
> 'Constant' variable guards dead code (DEADCODE) dead_error_line:
> Execution cannot reach this statement: prev_lops2->next = lops->next;.
> Local variable prev_lops2 is assigned only once, to a constant
> value, making it effectively constant throughout its scope. If this is
> not the intent, examine the logic to see if there is a missing
> assignment that would make prev_lops2 not remain constant.
>
> 2082 prev_lops2->next = lops->next;
> 2083 break;
> 2084 }
> 2085 up_write(&snd_ctl_layer_rwsem);
> 2086 }
>
> I couldn't quite figure out the original intent of the prev_lops use, so
> I'd thought I'd report this issue as the code does look incorrect.
Thank you. I submitted the fix here:
https://lore.kernel.org/alsa-devel/20210331180702.663489-1-perex@perex.cz/
Jaroslav
--
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
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