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[RFC] input/elants_i2c: Detect enum overflow

Message ID 59e2e82d1e40df11ab38874c03556a31c6b2f484.1612974132.git.jpoimboe@redhat.com (mailing list archive)
State Accepted
Commit ede6747c2f8975892ab98bed94357dc8c35d790c
Headers show
Series [RFC] input/elants_i2c: Detect enum overflow | expand

Commit Message

Josh Poimboeuf Feb. 10, 2021, 4:25 p.m. UTC 
If an enum value were to get added without updating this switch
statement, the unreachable() annotation would trigger undefined
behavior, causing execution to fall through the end of the function,
into the next one.

Make the error handling more robust for an unexpected enum value, by
doing BUG() instead of unreachable().

Fixes the following objtool warning:

  drivers/input/touchscreen/elants_i2c.o: warning: objtool: elants_i2c_initialize() falls through to next function elants_i2c_resume()

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 drivers/input/touchscreen/elants_i2c.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Michał Mirosław Feb. 11, 2021, 2:19 a.m. UTC | #1 
On Wed, Feb 10, 2021 at 10:25:28AM -0600, Josh Poimboeuf wrote:
> If an enum value were to get added without updating this switch
> statement, the unreachable() annotation would trigger undefined
> behavior, causing execution to fall through the end of the function,
> into the next one.
> 
> Make the error handling more robust for an unexpected enum value, by
> doing BUG() instead of unreachable().
> 
> Fixes the following objtool warning:
> 
>   drivers/input/touchscreen/elants_i2c.o: warning: objtool: elants_i2c_initialize() falls through to next function elants_i2c_resume()
> 
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Acked-by: Randy Dunlap <rdunlap@infradead.org>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>

> ---
>  drivers/input/touchscreen/elants_i2c.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
> index 6f57ec579f00..4c2b579f6c8b 100644
> --- a/drivers/input/touchscreen/elants_i2c.c
> +++ b/drivers/input/touchscreen/elants_i2c.c
> @@ -656,8 +656,7 @@ static int elants_i2c_initialize(struct elants_data *ts)
>  			error = elants_i2c_query_ts_info_ektf(ts);
>  		break;
>  	default:
> -		unreachable();
> -		break;
> +		BUG();
>  	}
>  
>  	if (error)
> -- 
> 2.29.2
>
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Patch

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
index 6f57ec579f00..4c2b579f6c8b 100644
--- a/drivers/input/touchscreen/elants_i2c.c
+++ b/drivers/input/touchscreen/elants_i2c.c
@@ -656,8 +656,7 @@  static int elants_i2c_initialize(struct elants_data *ts)
 			error = elants_i2c_query_ts_info_ektf(ts);
 		break;
 	default:
-		unreachable();
-		break;
+		BUG();
 	}
 
 	if (error)