Commit a3192688 authored by Jeff Layton's avatar Jeff Layton Committed by Trond Myklebust
Browse files

nfs: make nfs4_init_nonuniform_client_string use a dynamically allocated buffer 



The way the *_client_string functions work is a little goofy. They build
the string in an on-stack buffer and then use kstrdup to copy it. This
is not only stack-heavy but artificially limits the size of the client
name string. Change it so that we determine the length of the string,
allocate it and then scnprintf into it.

Since the contents of the nonuniform string depend on rcu-managed data
structures, it's possible that they'll change between when we allocate
the string and when we go to fill it. If that happens, free the string,
recalculate the length and try again. If it the mismatch isn't resolved
on the second try then just give up and return -EINVAL.

Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent b8fb2f59

fs/nfs/nfs4proc.c

+51 −23
Original line number Diff line number Diff line
@@ -4957,25 +4957,54 @@ static void nfs4_init_boot_verifier(const struct nfs_client *clp, 
	memcpy(bootverf->data, verf, sizeof(bootverf->data));

}



static unsigned int

nfs4_init_nonuniform_client_string(struct nfs_client *clp,

				   char *buf, size_t len)

static int

nfs4_init_nonuniform_client_string(struct nfs_client *clp)

{

	unsigned int result;

	int result;

	size_t len;

	char *str;

	bool retried = false;



	if (clp->cl_owner_id != NULL)

		return strlcpy(buf, clp->cl_owner_id, len);

		return 0;

retry:

	rcu_read_lock();

	len = 10 + strlen(clp->cl_ipaddr) + 1 +

		strlen(rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR)) +

		1 +

		strlen(rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_PROTO)) +

		1;

	rcu_read_unlock();



	if (len > NFS4_OPAQUE_LIMIT + 1)

		return -EINVAL;



	/*

	 * Since this string is allocated at mount time, and held until the

	 * nfs_client is destroyed, we can use GFP_KERNEL here w/o worrying

	 * about a memory-reclaim deadlock.

	 */

	str = kmalloc(len, GFP_KERNEL);

	if (!str)

		return -ENOMEM;



	rcu_read_lock();

	result = scnprintf(buf, len, "Linux NFSv4.0 %s/%s %s",

	result = scnprintf(str, len, "Linux NFSv4.0 %s/%s %s",

			clp->cl_ipaddr,

				rpc_peeraddr2str(clp->cl_rpcclient,

							RPC_DISPLAY_ADDR),

				rpc_peeraddr2str(clp->cl_rpcclient,

							RPC_DISPLAY_PROTO));

			rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR),

			rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_PROTO));

	rcu_read_unlock();

	clp->cl_owner_id = kstrdup(buf, GFP_KERNEL);

	return result;



	/* Did something change? */

	if (result >= len) {

		kfree(str);

		if (retried)

			return -EINVAL;

		retried = true;

		goto retry;

	}

	clp->cl_owner_id = str;

	return 0;

}



static unsigned int
@@ -5066,21 +5095,20 @@ int nfs4_proc_setclientid(struct nfs_client *clp, u32 program, 


	/* nfs_client_id4 */

	nfs4_init_boot_verifier(clp, &sc_verifier);

	if (test_bit(NFS_CS_MIGRATION, &clp->cl_flags))

	if (test_bit(NFS_CS_MIGRATION, &clp->cl_flags)) {

		setclientid.sc_name_len =

				nfs4_init_uniform_client_string(clp,

						setclientid.sc_name,

						sizeof(setclientid.sc_name));

	else

		setclientid.sc_name_len =

				nfs4_init_nonuniform_client_string(clp,

						setclientid.sc_name,

						sizeof(setclientid.sc_name));



		if (!clp->cl_owner_id) {

			status = -ENOMEM;

			goto out;

		}

	} else {

		status = nfs4_init_nonuniform_client_string(clp);

		if (status)

			goto out;

	}



	/* cb_client4 */

	setclientid.sc_netid_len =

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