linux-kernel - [PATCH linux-next] lockd: nlmsvc_mark

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Message-Id: <1360698538-63040-1-git-send-email-tim.gardner@canonical.com>
Date:	Tue, 12 Feb 2013 12:48:58 -0700
From:	Tim Gardner <tim.gardner@...onical.com>
To:	linux-kernel@...r.kernel.org
Cc:	Tim Gardner <tim.gardner@...onical.com>,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	"J. Bruce Fields" <bfields@...ldses.org>, linux-nfs@...r.kernel.org
Subject: [PATCH linux-next] lockd: nlmsvc_mark_resources(): avoid stack overflow

Dynamically allocate the NLM host structure in order to avoid stack overflow.
nlmsvc_mark_resources() is several call levels deep in a stack
that has a number of large variables. 512 bytes seems like a lot
on the stack at this point.

smatch analysis:

fs/lockd/svcsubs.c:366 nlmsvc_mark_resources() warn: 'hint' puts
 512 bytes on stack

Cc: Trond Myklebust <Trond.Myklebust@...app.com>
Cc: "J. Bruce Fields" <bfields@...ldses.org>
Cc: linux-nfs@...r.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@...onical.com>
---
 fs/lockd/svcsubs.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
index b904f41..f3abb7f 100644
--- a/fs/lockd/svcsubs.c
+++ b/fs/lockd/svcsubs.c
@@ -363,11 +363,15 @@ nlmsvc_is_client(void *data, struct nlm_host *dummy)
 void
 nlmsvc_mark_resources(struct net *net)
 {
-	struct nlm_host hint;
+	struct nlm_host *hint = kzalloc(sizeof(*hint), GFP_KERNEL);
 
-	dprintk("lockd: nlmsvc_mark_resources for net %p\n", net);
-	hint.net = net;
-	nlm_traverse_files(&hint, nlmsvc_mark_host, NULL);
+	if (hint) {
+		dprintk("lockd: nlmsvc_mark_resources for net %p\n", net);
+		hint->net = net;
+		nlm_traverse_files(hint, nlmsvc_mark_host, NULL);
+	}
+
+	kfree(hint);
 }
 
 /*
-- 
1.7.9.5

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