RE: [PATCH] Tools: hv: fix send/recv buffer allocation

[KY Srinivasan]

> -----Original Message-----
> From: Olaf Hering [mailto:olaf@xxxxxxxxx]
> Sent: Thursday, August 01, 2013 8:34 AM
> To: KY Srinivasan; gregkh@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; Olaf Hering
> Subject: [PATCH] Tools: hv: fix send/recv buffer allocation
> 
> hv_kvp_daemon fails to start in current openSuSE 13.1 snapshots because
> the kvp_send_buffer is too small to hold cn_msg+hv_kvp_msg, the very
> first sendmsg returns with EFAULT. In addition it fixes the Network info
> tab in Windows Server 2012R2 in SLES11.
> 
> Adjust the code in kvp and vss daemon to allocate the needed buffers at
> runtime. To keep the code simple, the buffer_len includes also the
> nlmsghdr, although only the recv_buffer needs this extra space.
> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>

> ---
>  tools/hv/hv_kvp_daemon.c | 15 ++++++++++++---
>  tools/hv/hv_vss_daemon.c | 15 ++++++++++++---
>  2 files changed, 24 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c
> index 07819bf..657c1d2 100644
> --- a/tools/hv/hv_kvp_daemon.c
> +++ b/tools/hv/hv_kvp_daemon.c
> @@ -79,8 +79,6 @@ enum {
>  	DNS
>  };
> 
> -static char kvp_send_buffer[4096];
> -static char kvp_recv_buffer[4096 * 2];
>  static struct sockaddr_nl addr;
>  static int in_hand_shake = 1;
> 
> @@ -1437,10 +1435,21 @@ int main(void)
>  	int	pool;
>  	char	*if_name;
>  	struct hv_kvp_ipaddr_value *kvp_ip_val;
> +	char *kvp_send_buffer;
> +	char *kvp_recv_buffer;
> +	size_t kvp_recv_buffer_len;
> 
>  	daemon(1, 0);
>  	openlog("KVP", 0, LOG_USER);
>  	syslog(LOG_INFO, "KVP starting; pid is:%d", getpid());
> +
> +	kvp_recv_buffer_len = NLMSG_HDRLEN + sizeof(struct cn_msg) +
> sizeof(struct hv_kvp_msg);
> +	kvp_send_buffer = calloc(1, kvp_recv_buffer_len);
> +	kvp_recv_buffer = calloc(1, kvp_recv_buffer_len);
> +	if (!(kvp_send_buffer && kvp_recv_buffer)) {
> +		syslog(LOG_ERR, "Failed to allocate netlink buffers");
> +		exit(EXIT_FAILURE);
> +	}
>  	/*
>  	 * Retrieve OS release information.
>  	 */
> @@ -1514,7 +1523,7 @@ int main(void)
>  				continue;
>  		}
> 
> -		len = recvfrom(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0,
> +		len = recvfrom(fd, kvp_recv_buffer, kvp_recv_buffer_len, 0,
>  				addr_p, &addr_l);
> 
>  		if (len < 0) {
> diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
> index fea03a3..4c34675 100644
> --- a/tools/hv/hv_vss_daemon.c
> +++ b/tools/hv/hv_vss_daemon.c
> @@ -38,8 +38,6 @@
>  #include <linux/netlink.h>
>  #include <syslog.h>
> 
> -static char vss_recv_buffer[4096];
> -static char vss_send_buffer[4096];
>  static struct sockaddr_nl addr;
> 
>  #ifndef SOL_NETLINK
> @@ -147,6 +145,9 @@ int main(void)
>  	struct cn_msg	*incoming_cn_msg;
>  	int	op;
>  	struct hv_vss_msg *vss_msg;
> +	char *vss_send_buffer;
> +	char *vss_recv_buffer;
> +	size_t vss_recv_buffer_len;
> 
>  	if (daemon(1, 0))
>  		return 1;
> @@ -154,6 +155,14 @@ int main(void)
>  	openlog("Hyper-V VSS", 0, LOG_USER);
>  	syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
> 
> +	vss_recv_buffer_len = NLMSG_HDRLEN + sizeof(struct cn_msg) +
> sizeof(struct hv_vss_msg);
> +	vss_send_buffer = calloc(1, vss_recv_buffer_len);
> +	vss_recv_buffer = calloc(1, vss_recv_buffer_len);
> +	if (!(vss_send_buffer && vss_recv_buffer)) {
> +		syslog(LOG_ERR, "Failed to allocate netlink buffers");
> +		exit(EXIT_FAILURE);
> +	}
> +
>  	fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
>  	if (fd < 0) {
>  		syslog(LOG_ERR, "netlink socket creation failed; error:%d", fd);
> @@ -201,7 +210,7 @@ int main(void)
>  		pfd.revents = 0;
>  		poll(&pfd, 1, -1);
> 
> -		len = recvfrom(fd, vss_recv_buffer, sizeof(vss_recv_buffer), 0,
> +		len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0,
>  				addr_p, &addr_l);
> 
>  		if (len < 0) {
> 
> 



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