@@ -599,14 +599,16 @@ EXPORT_SYMBOL_GPL(rpc_shutdown_client);
/*
* Free an RPC client
*/
-static void
+static struct rpc_clnt *
rpc_free_client(struct rpc_clnt *clnt)
{
+ struct rpc_clnt *parent = NULL;
+
dprintk_rcu("RPC: destroying %s client for %s\n",
clnt->cl_protname,
rcu_dereference(clnt->cl_xprt)->servername);
if (clnt->cl_parent != clnt)
- rpc_release_client(clnt->cl_parent);
+ parent = clnt->cl_parent;
rpc_unregister_client(clnt);
rpc_clnt_remove_pipedir(clnt);
rpc_free_iostats(clnt->cl_metrics);
@@ -615,18 +617,17 @@ rpc_free_client(struct rpc_clnt *clnt)
xprt_put(rcu_dereference_raw(clnt->cl_xprt));
rpciod_down();
kfree(clnt);
+ return parent;
}
/*
* Free an RPC client
*/
-static void
+static struct rpc_clnt *
rpc_free_auth(struct rpc_clnt *clnt)
{
- if (clnt->cl_auth == NULL) {
- rpc_free_client(clnt);
- return;
- }
+ if (clnt->cl_auth == NULL)
+ return rpc_free_client(clnt);
/*
* Note: RPCSEC_GSS may need to send NULL RPC calls in order to
@@ -637,7 +638,8 @@ rpc_free_auth(struct rpc_clnt *clnt)
rpcauth_release(clnt->cl_auth);
clnt->cl_auth = NULL;
if (atomic_dec_and_test(&clnt->cl_count))
- rpc_free_client(clnt);
+ return rpc_free_client(clnt);
+ return NULL;
}
/*
@@ -648,10 +650,13 @@ rpc_release_client(struct rpc_clnt *clnt)
{
dprintk("RPC: rpc_release_client(%p)\n", clnt);
- if (list_empty(&clnt->cl_tasks))
- wake_up(&destroy_wait);
- if (atomic_dec_and_test(&clnt->cl_count))
- rpc_free_auth(clnt);
+ do {
+ if (list_empty(&clnt->cl_tasks))
+ wake_up(&destroy_wait);
+ if (!atomic_dec_and_test(&clnt->cl_count))
+ break;
+ clnt = rpc_free_auth(clnt);
+ } while (clnt != NULL);
}
/**
This is a note to let you know that I have just added a patch titled SUNRPC: Avoid deep recursion in rpc_release_client to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 2c4dcebb12f64df58d90a2e6c6f3d2b991e603e4 Mon Sep 17 00:00:00 2001 From: Trond Myklebust <Trond.Myklebust@netapp.com> Date: Tue, 12 Nov 2013 17:24:36 -0500 Subject: SUNRPC: Avoid deep recursion in rpc_release_client commit d07ba8422f1e58be94cc98a1f475946dc1b89f1b upstream. In cases where an rpc client has a parent hierarchy, then rpc_free_client may end up calling rpc_release_client() on the parent, thus recursing back into rpc_free_client. If the hierarchy is deep enough, then we can get into situations where the stack simply overflows. The fix is to have rpc_release_client() loop so that it can take care of the parent rpc client hierarchy without needing to recurse. Reported-by: Jeff Layton <jlayton@redhat.com> Reported-by: Weston Andros Adamson <dros@netapp.com> Reported-by: Bruce Fields <bfields@fieldses.org> Link: http://lkml.kernel.org/r/2C73011F-0939-434C-9E4D-13A1EB1403D7@netapp.com Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> [ luis: backported to 3.5: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/sunrpc/clnt.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) -- 1.8.3.2