linux-kernel - [ 075/103] svcrpc: fix handling of too-short rpcs

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Date:	Tue, 23 Jul 2013 15:26:26 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, "J. Bruce Fields" <bfields@...hat.com>
Subject: [ 075/103] svcrpc: fix handling of too-short rpcs

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "J. Bruce Fields" <bfields@...hat.com>

commit cf3aa02cb4a0c5af5557dd47f15a08a7df33182a upstream.

If we detect that an rpc is too short, we abort and close the
connection.  Except, there's a bug here: we're leaving sk_datalen
nonzero without leaving any pages in the sk_pages array.  The most
likely result of the inconsistency is a subsequent crash in
svc_tcp_clear_pages.

Also demote the BUG_ON in svc_tcp_clear_pages to a WARN.

Signed-off-by: J. Bruce Fields <bfields@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/sunrpc/svcsock.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -917,7 +917,10 @@ static void svc_tcp_clear_pages(struct s
 	len = svsk->sk_datalen;
 	npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	for (i = 0; i < npages; i++) {
-		BUG_ON(svsk->sk_pages[i] == NULL);
+		if (svsk->sk_pages[i] == NULL) {
+			WARN_ON_ONCE(1);
+			continue;
+		}
 		put_page(svsk->sk_pages[i]);
 		svsk->sk_pages[i] = NULL;
 	}
@@ -1092,8 +1095,10 @@ static int svc_tcp_recvfrom(struct svc_r
 		goto err_noclose;
 	}
 
-	if (svc_sock_reclen(svsk) < 8)
+	if (svc_sock_reclen(svsk) < 8) {
+		svsk->sk_datalen = 0;
 		goto err_delete; /* client is nuts. */
+	}
 
 	rqstp->rq_arg.len = svsk->sk_datalen;
 	rqstp->rq_arg.page_base = 0;


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