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Commit 1f70ef96 authored by Alexey Khoroshilov's avatar Alexey Khoroshilov Committed by Trond Myklebust
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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: default avatarAlexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 411a99ad

fs/nfs/client.c

+5 −3
Original line number Original line Diff line number Diff line
@@ -110,8 +110,8 @@ struct nfs_subversion *get_nfs_version(unsigned int version) 
		mutex_unlock(&nfs_version_mutex);

		mutex_unlock(&nfs_version_mutex);

	}

	}





	if (!IS_ERR(nfs))

	if (!IS_ERR(nfs) && !try_module_get(nfs->owner))

		try_module_get(nfs->owner);

		return ERR_PTR(-EAGAIN);

	return nfs;

	return nfs;

}

}
@@ -158,7 +158,8 @@ struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init) 
		goto error_0;

		goto error_0;





	clp->cl_nfs_mod = cl_init->nfs_mod;

	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;

	clp->rpc_ops = clp->cl_nfs_mod->rpc_ops;
@@ -190,6 +191,7 @@ struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init) 




error_cleanup:

error_cleanup:

	put_nfs_version(clp->cl_nfs_mod);

	put_nfs_version(clp->cl_nfs_mod);

error_dealloc:

	kfree(clp);

	kfree(clp);

error_0:

error_0:

	return ERR_PTR(err);

	return ERR_PTR(err);