> On Mar 24, 2022, at 5:33 PM, trondmy@xxxxxxxxxx wrote:
>
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>
> Do not cast the struct xprt to a sock_xprt unless we know it is a UDP or
> TCP transport. Otherwise the call to lock the mutex will scribble over
> whatever structure is actually there. This has been seen to cause hard
> system lockups when the underlying transport was RDMA.
>
> Fixes: e44773daf851 ("SUNRPC: Add srcaddr as a file in sysfs")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> net/sunrpc/sysfs.c | 32 ++++++++++++++++++++++----------
> 1 file changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/net/sunrpc/sysfs.c b/net/sunrpc/sysfs.c
> index 05c758da6a92..8ce053f84421 100644
> --- a/net/sunrpc/sysfs.c
> +++ b/net/sunrpc/sysfs.c
> @@ -107,22 +107,34 @@ static ssize_t rpc_sysfs_xprt_srcaddr_show(struct kobject *kobj,
> struct rpc_xprt *xprt = rpc_sysfs_xprt_kobj_get_xprt(kobj);
> struct sockaddr_storage saddr;
> struct sock_xprt *sock;
> + const char *fmt = "<closed>\n";
> ssize_t ret = -1;
>
> - if (!xprt || !xprt_connected(xprt)) {
> - xprt_put(xprt);
> - return -ENOTCONN;
> - }
> + if (!xprt || !xprt_connected(xprt))
> + goto out;
>
> - sock = container_of(xprt, struct sock_xprt, xprt);
> - mutex_lock(&sock->recv_mutex);
> - if (sock->sock == NULL ||
> - kernel_getsockname(sock->sock, (struct sockaddr *)&saddr) < 0)
This would be a little nicer if it went through the transport
switch instead. But isn't the socket address available in the
rpc_xprt?
> + switch (xprt->xprt_class->ident) {
> + case XPRT_TRANSPORT_UDP:
> + case XPRT_TRANSPORT_TCP:
> + break;
> + default:
> + fmt = "<not a socket>\n";
> goto out;
> + };
>
> - ret = sprintf(buf, "%pISc\n", &saddr);
> -out:
> + sock = container_of(xprt, struct sock_xprt, xprt);
> + mutex_lock(&sock->recv_mutex);
> + if (sock->sock != NULL) {
> + ret = kernel_getsockname(sock->sock, (struct sockaddr *)&saddr);
> + if (ret >= 0) {
> + ret = sprintf(buf, "%pISc\n", &saddr);
> + fmt = NULL;
> + }
> + }
> mutex_unlock(&sock->recv_mutex);
> +out:
> + if (fmt)
> + ret = sprintf(buf, fmt);
> xprt_put(xprt);
> return ret + 1;
> }
> --
> 2.35.1
>
--
Chuck Lever
