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@xxxxxxxx>
> 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@xxxxxxxx/
Jaroslav
--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
