From 576acc259146af848cec0940f573f7125a116b9f Mon Sep 17 00:00:00 2001 From: Scott Mayhew Date: Wed, 3 Nov 2021 06:24:40 -0400 Subject: [PATCH] nfs4: take a reference on the nfs_client when running FREE_STATEID During umount, the session slot tables are freed. If there are outstanding FREE_STATEID tasks, a use-after-free and slab corruption can occur when rpc_exit_task calls rpc_call_done -> nfs41_sequence_done -> nfs4_sequence_process/nfs41_sequence_free_slot. Prevent that from happening by taking a reference on the nfs_client in nfs41_free_stateid and putting it in nfs41_free_stateid_release. Signed-off-by: Scott Mayhew Signed-off-by: Trond Myklebust --- fs/nfs/nfs4proc.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 1c94f54..127388f 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -10115,6 +10115,10 @@ static void nfs41_free_stateid_done(struct rpc_task *task, void *calldata) static void nfs41_free_stateid_release(void *calldata) { + struct nfs_free_stateid_data *data = calldata; + struct nfs_client *clp = data->server->nfs_client; + + nfs_put_client(clp); kfree(calldata); } @@ -10151,6 +10155,10 @@ static int nfs41_free_stateid(struct nfs_server *server, }; struct nfs_free_stateid_data *data; struct rpc_task *task; + struct nfs_client *clp = server->nfs_client; + + if (!refcount_inc_not_zero(&clp->cl_count)) + return -EIO; nfs4_state_protect(server->nfs_client, NFS_SP4_MACH_CRED_STATEID, &task_setup.rpc_client, &msg); -- 2.7.4