Re: [PATCH 08/14] svcrpc: ignore unknown address type in udp receive

["J. Bruce Fields" <bfields@fieldses.org>]

On Tue, Aug 21, 2012 at 05:02:14PM -0400, Chuck Lever wrote:
> 
> On Aug 21, 2012, at 4:57 PM, J. Bruce Fields wrote:
> 
> > From: "J. Bruce Fields" <bfields@redhat.com>
> > 
> > How would this happen?
> 
> If an unsupported address family is used in the rqstp.

Right, but that's impossible, isn't it?

> > In any case, it appears this would be returned all the way up to the
> > caller of svc_recv(), and it's obvious that none of them are equipped to
> > handle it, and not clear what they would want to do with it anyway.
> > Let's just drop this and return -EAGAIN.
> 
> EAGAIN is incorrect; the correct error code is EAFNOSUPPORT.  If callers are not prepared for this error return, perhaps BUG_ON() would be more appropriate here.

Yeah.  Actually on a quick check this is the only caller that even
checks for this case.  So probably the check should go in svc_addr_len.
Maybe we should be nice and make it a warning.

--b.

commit 4814e806a44f3dee8f7cae00a7d0240487d62583
Author: J. Bruce Fields <bfields@redhat.com>
Date:   Tue Aug 21 17:22:11 2012 -0400

    svcrpc: don't bother checking bad svc_addr_len result
    
    None of the callers should see an unsupported address family (only one
    of them even bothers to check for that case), so just check for the
    buggy case in svc_addr_len and don't bother elsewhere.
    
    Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index b3f64b1..9324008 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -166,7 +166,7 @@ static inline size_t svc_addr_len(const struct sockaddr *sa)
 	case AF_INET6:
 		return sizeof(struct sockaddr_in6);
 	}
-
+	WARN_ONCE(true, "unknown address family %d\n", sa->sa_family);
 	return 0;
 }
 
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 998aa8c..13b005c 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -601,8 +601,6 @@ static int svc_udp_recvfrom(struct svc_rqst *rqstp)
 		return -EAGAIN;
 	}
 	len = svc_addr_len(svc_addr(rqstp));
-	if (len == 0)
-		return -EAFNOSUPPORT;
 	rqstp->rq_addrlen = len;
 	if (skb->tstamp.tv64 == 0) {
 		skb->tstamp = ktime_get_real();