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| author | Al Viro <viro@zeniv.linux.org.uk> | 2023-09-28 05:11:26 +0300 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2024-02-25 10:10:32 +0300 |
| commit | c1b967d03c5d570ed7b90a88031fa2af34bf5b20 (patch) | |
| tree | 230fde52c95cc00c8d08bdc2a49d119ccd79a325 /fs/nfs | |
| parent | 10a973fc4fb22390a8d362dd3265ec2c9a81d84c (diff) | |
| download | linux-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/nfs')
| -rw-r--r-- | fs/nfs/client.c | 13 |
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); |