Subject: Re: [PATCH 2/2] mac80211: Free mpath object when rhashtable insertion fails

From: Dan Carpenter <[email-masked]>
Date: Thu, 14 Feb 2019 08:52:00 +0300

Hi Herbert,

url:    https://github.com/0day-ci/linux/commits/Herbert-Xu/mac80211-Fix-incorrect-usage-of-rhashtable-walk-API/20190213-181325
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git master

smatch warnings:
net/mac80211/mesh_pathtbl.c:439 mesh_path_add() warn: passing zero to 'ERR_PTR'

# https://github.com/0day-ci/linux/commit/a0886e834aacf883ceaf0c34c842c4cdb4d318fd
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout a0886e834aacf883ceaf0c34c842c4cdb4d318fd
vim +/ERR_PTR +439 net/mac80211/mesh_pathtbl.c

b15dc38b9 Bob Copeland         2016-02-28  390  
eb2b9311f Luis Carlos Cobo     2008-02-23  391  /**
eb2b9311f Luis Carlos Cobo     2008-02-23  392   * mesh_path_add - allocate and add a new path to the mesh path table
bf7cd94dc Johannes Berg        2013-02-15  393   * @dst: destination address of the path (ETH_ALEN length)
f698d856f Jasper Bryant-Greene 2008-08-03  394   * @sdata: local subif
eb2b9311f Luis Carlos Cobo     2008-02-23  395   *
af901ca18 André Goddard Rosa   2009-11-14  396   * Returns: 0 on success
eb2b9311f Luis Carlos Cobo     2008-02-23  397   *
eb2b9311f Luis Carlos Cobo     2008-02-23  398   * State: the initial state of the new path is set to 0
eb2b9311f Luis Carlos Cobo     2008-02-23  399   */
ae76eef02 Bob Copeland         2013-03-29  400  struct mesh_path *mesh_path_add(struct ieee80211_sub_if_data *sdata,
ae76eef02 Bob Copeland         2013-03-29  401  				const u8 *dst)
eb2b9311f Luis Carlos Cobo     2008-02-23  402  {
349eb8cf4 Johannes Berg        2011-05-14  403  	struct mesh_table *tbl;
eb2b9311f Luis Carlos Cobo     2008-02-23  404  	struct mesh_path *mpath, *new_mpath;
60854fd94 Bob Copeland         2016-03-02  405  	int ret;
eb2b9311f Luis Carlos Cobo     2008-02-23  406  
b203ca391 Joe Perches          2012-05-08  407  	if (ether_addr_equal(dst, sdata->vif.addr))
eb2b9311f Luis Carlos Cobo     2008-02-23  408  		/* never add ourselves as neighbours */
ae76eef02 Bob Copeland         2013-03-29  409  		return ERR_PTR(-ENOTSUPP);
eb2b9311f Luis Carlos Cobo     2008-02-23  410  
eb2b9311f Luis Carlos Cobo     2008-02-23  411  	if (is_multicast_ether_addr(dst))
ae76eef02 Bob Copeland         2013-03-29  412  		return ERR_PTR(-ENOTSUPP);
eb2b9311f Luis Carlos Cobo     2008-02-23  413  
472dbc45d Johannes Berg        2008-09-11  414  	if (atomic_add_unless(&sdata->u.mesh.mpaths, 1, MESH_MAX_MPATHS) == 0)
ae76eef02 Bob Copeland         2013-03-29  415  		return ERR_PTR(-ENOSPC);
ae76eef02 Bob Copeland         2013-03-29  416  
b15dc38b9 Bob Copeland         2016-02-28  417  	new_mpath = mesh_path_new(sdata, dst, GFP_ATOMIC);
402d7752e Pavel Emelyanov      2008-05-06  418  	if (!new_mpath)
60854fd94 Bob Copeland         2016-03-02  419  		return ERR_PTR(-ENOMEM);
402d7752e Pavel Emelyanov      2008-05-06  420  
60854fd94 Bob Copeland         2016-03-02  421  	tbl = sdata->u.mesh.mesh_paths;
60854fd94 Bob Copeland         2016-03-02  422  	do {
60854fd94 Bob Copeland         2016-03-02  423  		ret = rhashtable_lookup_insert_fast(&tbl->rhead,
60854fd94 Bob Copeland         2016-03-02  424  						    &new_mpath->rhash,
60854fd94 Bob Copeland         2016-03-02  425  						    mesh_rht_params);
f84e71a94 Pavel Emelyanov      2008-05-06  426  
60854fd94 Bob Copeland         2016-03-02  427  		if (ret == -EEXIST)
60854fd94 Bob Copeland         2016-03-02  428  			mpath = rhashtable_lookup_fast(&tbl->rhead,
60854fd94 Bob Copeland         2016-03-02  429  						       dst,
60854fd94 Bob Copeland         2016-03-02  430  						       mesh_rht_params);
05b0152f1 Herbert Xu           2019-02-13  431  		else if (!ret)
05b0152f1 Herbert Xu           2019-02-13  432  			hlist_add_head(&new_mpath->walk_list, &tbl->walk_head);
60854fd94 Bob Copeland         2016-03-02  433  	} while (unlikely(ret == -EEXIST && !mpath));
f5ea9120b Johannes Berg        2009-08-07  434  
a0886e834 Herbert Xu           2019-02-13  435  	if (ret)
a0886e834 Herbert Xu           2019-02-13  436  		kfree(new_mpath);
a0886e834 Herbert Xu           2019-02-13  437  
a0886e834 Herbert Xu           2019-02-13  438  	if (ret != -EEXIST)
60854fd94 Bob Copeland         2016-03-02 @439  		return ERR_PTR(ret);

                                                         if (ret && ret != -EEXIST) ?

ae76eef02 Bob Copeland         2013-03-29  440  
60854fd94 Bob Copeland         2016-03-02  441  	/* At this point either new_mpath was added, or we found a
60854fd94 Bob Copeland         2016-03-02  442  	 * matching entry already in the table; in the latter case
60854fd94 Bob Copeland         2016-03-02  443  	 * free the unnecessary new entry.
60854fd94 Bob Copeland         2016-03-02  444  	 */
a0886e834 Herbert Xu           2019-02-13  445  	if (ret == -EEXIST)
60854fd94 Bob Copeland         2016-03-02  446  		new_mpath = mpath;
60854fd94 Bob Copeland         2016-03-02  447  	sdata->u.mesh.mesh_paths_generation++;
60854fd94 Bob Copeland         2016-03-02  448  	return new_mpath;
18889231e Javier Cardona       2009-08-10  449  }
eb2b9311f Luis Carlos Cobo     2008-02-23  450  

:::::: The code at line 439 was first introduced by commit
:::::: 60854fd94573f0d3b80b55b40cf0140a0430f3ab mac80211: mesh: convert path table to rhashtable

:::::: TO: Bob Copeland <[email-masked]>
:::::: CC: Johannes Berg <[email-masked]>

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