[PATCH] ALSA: seq: initialize whole fields of automatic variable with union type

[PATCH] ALSA: seq: initialize whole fields of automatic variable with union type

[Takashi Sakamoto]

Currently, automatic variable of 'union ioctl_arg' type is initialized
by designated initialization. Although, the actual effect is interpretation
of early element of int type and initialization of 'int pversion'.
Therefore the first field corresponding to int type is initialized to zero.
This is against my expectation to initialize whole fields.

This commit uses memset() to initialize the variable, instead of designated
initialization.

Fixes: 04a56dd8ed0d ('ALSA: seq: change ioctl command operation to get data in kernel space')
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 sound/core/seq/seq_clientmgr.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
index 286394b..fd50c38 100644
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -2100,7 +2100,7 @@ static long snd_seq_ioctl(struct file *file, unsigned int cmd,
 		struct snd_seq_client_pool	client_pool;
 		struct snd_seq_remove_events	remove_events;
 		struct snd_seq_query_subs	query_subs;
-	} buf = {0};
+	} buf;
 	const struct ioctl_handler *handler;
 	unsigned long size;
 	int err;
@@ -2114,6 +2114,9 @@ static long snd_seq_ioctl(struct file *file, unsigned int cmd,
 	}
 	if (handler->cmd == 0)
 		return -ENOTTY;
+
+	memset(&buf, 0, sizeof(union ioctl_arg));
+
 	/*
 	 * All of ioctl commands for ALSA sequencer get an argument of size
 	 * within 13 bits. We can safely pick up the size from the command.
-- 
2.7.4

Re: [PATCH] ALSA: seq: initialize whole fields of automatic variable with union type

[Takashi Iwai]

On Tue, 30 Aug 2016 02:11:54 +0200,
Takashi Sakamoto wrote:
> 
> Currently, automatic variable of 'union ioctl_arg' type is initialized
> by designated initialization. Although, the actual effect is interpretation
> of early element of int type and initialization of 'int pversion'.
> Therefore the first field corresponding to int type is initialized to zero.
> This is against my expectation to initialize whole fields.
> 
> This commit uses memset() to initialize the variable, instead of designated
> initialization.
> 
> Fixes: 04a56dd8ed0d ('ALSA: seq: change ioctl command operation to get data in kernel space')
> Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
> ---
>  sound/core/seq/seq_clientmgr.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
> index 286394b..fd50c38 100644
> --- a/sound/core/seq/seq_clientmgr.c
> +++ b/sound/core/seq/seq_clientmgr.c
> @@ -2100,7 +2100,7 @@ static long snd_seq_ioctl(struct file *file, unsigned int cmd,
>  		struct snd_seq_client_pool	client_pool;
>  		struct snd_seq_remove_events	remove_events;
>  		struct snd_seq_query_subs	query_subs;
> -	} buf = {0};
> +	} buf;
>  	const struct ioctl_handler *handler;
>  	unsigned long size;
>  	int err;
> @@ -2114,6 +2114,9 @@ static long snd_seq_ioctl(struct file *file, unsigned int cmd,
>  	}
>  	if (handler->cmd == 0)
>  		return -ENOTTY;
> +
> +	memset(&buf, 0, sizeof(union ioctl_arg));

The common practice is to pass sizeof(buf).


Takashi

Re: [PATCH] ALSA: seq: initialize whole fields of automatic variable with union type

[Takashi Sakamoto]

On Aug 30 2016 14:11, Takashi Iwai wrote:
> On Tue, 30 Aug 2016 02:11:54 +0200,
> Takashi Sakamoto wrote:
>>
>> Currently, automatic variable of 'union ioctl_arg' type is initialized
>> by designated initialization. Although, the actual effect is interpretation
>> of early element of int type and initialization of 'int pversion'.
>> Therefore the first field corresponding to int type is initialized to zero.
>> This is against my expectation to initialize whole fields.
>>
>> This commit uses memset() to initialize the variable, instead of designated
>> initialization.
>>
>> Fixes: 04a56dd8ed0d ('ALSA: seq: change ioctl command operation to get data in kernel space')
>> Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
>> ---
>>  sound/core/seq/seq_clientmgr.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
>> index 286394b..fd50c38 100644
>> --- a/sound/core/seq/seq_clientmgr.c
>> +++ b/sound/core/seq/seq_clientmgr.c
>> @@ -2100,7 +2100,7 @@ static long snd_seq_ioctl(struct file *file, unsigned int cmd,
>>  		struct snd_seq_client_pool	client_pool;
>>  		struct snd_seq_remove_events	remove_events;
>>  		struct snd_seq_query_subs	query_subs;
>> -	} buf = {0};
>> +	} buf;
>>  	const struct ioctl_handler *handler;
>>  	unsigned long size;
>>  	int err;
>> @@ -2114,6 +2114,9 @@ static long snd_seq_ioctl(struct file *file, unsigned int cmd,
>>  	}
>>  	if (handler->cmd == 0)
>>  		return -ENOTTY;
>> +
>> +	memset(&buf, 0, sizeof(union ioctl_arg));
>
> The common practice is to pass sizeof(buf).

OK. I'll post revised version later.


Regards

Takashi Sakamoto