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authorAl Viro <viro@zeniv.linux.org.uk>2023-09-28 05:11:26 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2024-02-25 10:10:32 +0300
commitc1b967d03c5d570ed7b90a88031fa2af34bf5b20 (patch)
tree230fde52c95cc00c8d08bdc2a49d119ccd79a325 /fs
parent10a973fc4fb22390a8d362dd3265ec2c9a81d84c (diff)
downloadlinux-c1b967d03c5d570ed7b90a88031fa2af34bf5b20.tar.xz
nfs: fix UAF on pathwalk running into umount
NFS ->d_revalidate(), ->permission() and ->get_link() need to access some parts of nfs_server when called in RCU mode: server->flags server->caps *(server->io_stats) and, worst of all, call server->nfs_client->rpc_ops->have_delegation (the last one - as NFS_PROTO(inode)->have_delegation()). We really don't want to RCU-delay the entire nfs_free_server() (it would have to be done with schedule_work() from RCU callback, since it can't be made to run from interrupt context), but actual freeing of nfs_server and ->io_stats can be done via call_rcu() just fine. nfs_client part is handled simply by making nfs_free_client() use kfree_rcu(). Acked-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/nfs/client.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 44eca51b2808..fbdc9ca80f71 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -246,7 +246,7 @@ void nfs_free_client(struct nfs_client *clp)
put_nfs_version(clp->cl_nfs_mod);
kfree(clp->cl_hostname);
kfree(clp->cl_acceptor);
- kfree(clp);
+ kfree_rcu(clp, rcu);
}
EXPORT_SYMBOL_GPL(nfs_free_client);
@@ -1006,6 +1006,14 @@ struct nfs_server *nfs_alloc_server(void)
}
EXPORT_SYMBOL_GPL(nfs_alloc_server);
+static void delayed_free(struct rcu_head *p)
+{
+ struct nfs_server *server = container_of(p, struct nfs_server, rcu);
+
+ nfs_free_iostats(server->io_stats);
+ kfree(server);
+}
+
/*
* Free up a server record
*/
@@ -1031,10 +1039,9 @@ void nfs_free_server(struct nfs_server *server)
ida_destroy(&server->lockowner_id);
ida_destroy(&server->openowner_id);
- nfs_free_iostats(server->io_stats);
put_cred(server->cred);
- kfree(server);
nfs_release_automount_timer();
+ call_rcu(&server->rcu, delayed_free);
}
EXPORT_SYMBOL_GPL(nfs_free_server);