linux-kernel - [patch 112/123] NFS: Fix an allocation-under-spinlock bug

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Message-Id: <20100313001514.929300670@kvm.kroah.org>
Date:	Fri, 12 Mar 2010 16:13:30 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Trond Myklebust <Trond.Myklebust@...app.com>
Subject: [patch 112/123] NFS: Fix an allocation-under-spinlock bug

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

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

From: Trond Myklebust <Trond.Myklebust@...app.com>

commit ebed9203b68a4f333ce5d17e874b26c3afcfeff1 upstream.

sunrpc_cache_update() will always call detail->update() from inside the
detail->hash_lock, so it cannot allocate memory.

Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 fs/nfs/dns_resolve.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -36,6 +36,19 @@ struct nfs_dns_ent {
 };
 
 
+static void nfs_dns_ent_update(struct cache_head *cnew,
+		struct cache_head *ckey)
+{
+	struct nfs_dns_ent *new;
+	struct nfs_dns_ent *key;
+
+	new = container_of(cnew, struct nfs_dns_ent, h);
+	key = container_of(ckey, struct nfs_dns_ent, h);
+
+	memcpy(&new->addr, &key->addr, key->addrlen);
+	new->addrlen = key->addrlen;
+}
+
 static void nfs_dns_ent_init(struct cache_head *cnew,
 		struct cache_head *ckey)
 {
@@ -49,8 +62,7 @@ static void nfs_dns_ent_init(struct cach
 	new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
 	if (new->hostname) {
 		new->namelen = key->namelen;
-		memcpy(&new->addr, &key->addr, key->addrlen);
-		new->addrlen = key->addrlen;
+		nfs_dns_ent_update(cnew, ckey);
 	} else {
 		new->namelen = 0;
 		new->addrlen = 0;
@@ -234,7 +246,7 @@ static struct cache_detail nfs_dns_resol
 	.cache_show = nfs_dns_show,
 	.match = nfs_dns_match,
 	.init = nfs_dns_ent_init,
-	.update = nfs_dns_ent_init,
+	.update = nfs_dns_ent_update,
 	.alloc = nfs_dns_ent_alloc,
 };
 


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