NFS: add checks for returned value of try_module_get()
There is a couple of places in client code where returned value
of try_module_get() is ignored. As a result there is a small chance
to premature unload module because of unbalanced refcounting.
The patch adds error handling in that places.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 168aa0d..b7bfa27 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -110,8 +110,8 @@
mutex_unlock(&nfs_version_mutex);
}
- if (!IS_ERR(nfs))
- try_module_get(nfs->owner);
+ if (!IS_ERR(nfs) && !try_module_get(nfs->owner))
+ return ERR_PTR(-EAGAIN);
return nfs;
}
@@ -158,7 +158,8 @@
goto error_0;
clp->cl_nfs_mod = cl_init->nfs_mod;
- try_module_get(clp->cl_nfs_mod->owner);
+ if (!try_module_get(clp->cl_nfs_mod->owner))
+ goto error_dealloc;
clp->rpc_ops = clp->cl_nfs_mod->rpc_ops;
@@ -190,6 +191,7 @@
error_cleanup:
put_nfs_version(clp->cl_nfs_mod);
+error_dealloc:
kfree(clp);
error_0:
return ERR_PTR(err);
