[dm-devel] [PATCH] multipathd: fix memory allocation logic error for polls in uxsock_listen()

[Hannes Reinecke]

On 08/10/2016 11:32 AM, tang.junhui at zte.com.cn wrote:
> From: "tang.junhui" <tang.junhui at zte.com.cn>
> 
> logic error exists in memory allocation for polls in uxsock_listen(), even if the allocated memory size meet the needs, it is still to realloc memory, which is not up to expectations.
> 
> Signed-off-by: tang.junhui <tang.junhui at zte.com.cn>
> ---
>  multipathd/uxlsnr.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c
> index f114e59..fa29b2a 100644
> --- a/multipathd/uxlsnr.c
> +++ b/multipathd/uxlsnr.c
> @@ -145,7 +145,7 @@ void * uxsock_listen(uxsock_trigger_fn uxsock_trigger, void * trigger_data)
>  	pthread_cleanup_push(uxsock_cleanup, NULL);
>  
>  	condlog(3, "uxsock: startup listener");
> -	polls = (struct pollfd *)MALLOC(MIN_POLLS + 1);
> +	polls = (struct pollfd *)MALLOC((MIN_POLLS + 1) * sizeof(struct pollfd));
>  	if (!polls) {
>  		condlog(0, "uxsock: failed to allocate poll fds");
>  		return NULL;
> @@ -167,9 +167,11 @@ void * uxsock_listen(uxsock_trigger_fn uxsock_trigger, void * trigger_data)
>  		}
>  		if (num_clients != old_clients) {
>  			struct pollfd *new;
> -			if (num_clients < MIN_POLLS) {
> +			if (num_clients <= MIN_POLLS && old_clients > MIN_POLLS) {
>  				new = REALLOC(polls, (1 + MIN_POLLS) *
>  						sizeof(struct pollfd));
> +			} else if (num_clients <= MIN_POLLS && old_clients <= MIN_POLLS) {
> +				new = polls;
>  			} else {
>  				new = REALLOC(polls, (1+num_clients) *
>  						sizeof(struct pollfd));
> @@ -181,7 +183,7 @@ void * uxsock_listen(uxsock_trigger_fn uxsock_trigger, void * trigger_data)
>  				pthread_yield();
>  				continue;
>  			}
> -			num_clients = old_clients;
> +			old_clients = num_clients;
>  			polls = new;
>  		}
>  		polls[0].fd = ux_sock;
> 
Thanks for catching this.

Reviewed-by: Hannes Reinecke <hare at suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare at suse.de			               +49 911 74053 688
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