Re: [PATCH] NFS: Fixes for nfs4_proc_mkdir() error handling

[Dan Carpenter <dan.carpenter@linaro.org>]

Hi Anna,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Anna-Schumaker/NFS-Fixes-for-nfs4_proc_mkdir-error-handling/20250516-231124
base:   git://git.linux-nfs.org/projects/trondmy/linux-nfs.git linux-next
patch link:    https://lore.kernel.org/r/20250516150010.61641-1-anna%40kernel.org
patch subject: [PATCH] NFS: Fixes for nfs4_proc_mkdir() error handling
config: i386-randconfig-141-20250517 (https://download.01.org/0day-ci/archive/20250518/202505181116.RhlCb75I-lkp@intel.com/config)
compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202505181116.RhlCb75I-lkp@intel.com/

New smatch warnings:
fs/nfs/nfs4proc.c:5277 nfs4_proc_mkdir() warn: passing zero to 'PTR_ERR'

vim +/PTR_ERR +5277 fs/nfs/nfs4proc.c

8376583b84a193 NeilBrown           2025-02-27  5260  static struct dentry *nfs4_proc_mkdir(struct inode *dir, struct dentry *dentry,
^1da177e4c3f41 Linus Torvalds      2005-04-16  5261  				      struct iattr *sattr)
^1da177e4c3f41 Linus Torvalds      2005-04-16  5262  {
dff25ddb48086a Andreas Gruenbacher 2016-12-02  5263  	struct nfs_server *server = NFS_SERVER(dir);
0688e64bc60038 Trond Myklebust     2019-04-07  5264  	struct nfs4_exception exception = {
0688e64bc60038 Trond Myklebust     2019-04-07  5265  		.interruptible = true,
0688e64bc60038 Trond Myklebust     2019-04-07  5266  	};
c528f70f504434 Trond Myklebust     2022-10-19  5267  	struct nfs4_label l, *label;
8376583b84a193 NeilBrown           2025-02-27  5268  	struct dentry *alias;
^1da177e4c3f41 Linus Torvalds      2005-04-16  5269  	int err;
a8a5da996df7d2 Aneesh Kumar K.V    2010-12-09  5270  
aa9c2669626ca7 David Quigley       2013-05-22  5271  	label = nfs4_label_init_security(dir, dentry, sattr, &l);
aa9c2669626ca7 David Quigley       2013-05-22  5272  
dff25ddb48086a Andreas Gruenbacher 2016-12-02  5273  	if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
a8a5da996df7d2 Aneesh Kumar K.V    2010-12-09  5274  		sattr->ia_mode &= ~current_umask();
^1da177e4c3f41 Linus Torvalds      2005-04-16  5275  	do {
8376583b84a193 NeilBrown           2025-02-27  5276  		alias = _nfs4_proc_mkdir(dir, dentry, sattr, label);
4c35d65f4c6f1e Anna Schumaker      2025-05-16 @5277  		err = PTR_ERR(alias);
4c35d65f4c6f1e Anna Schumaker      2025-05-16  5278  		if (err > 0)
4c35d65f4c6f1e Anna Schumaker      2025-05-16  5279  			err = 0;

This doesn't work.  Imagine we are on a 64bit system and
_nfs4_proc_mkdir() returns a valid pointer.  It depends on if BIT(31)
is set whether we return zero or a random negative number.

This needs to be:

	err = PTR_ERR_OR_ZERO(alias);

078ea3dfe396b1 Trond Myklebust     2013-08-12  5280  		trace_nfs4_mkdir(dir, &dentry->d_name, err);
078ea3dfe396b1 Trond Myklebust     2013-08-12  5281  		err = nfs4_handle_exception(NFS_SERVER(dir), err,
^1da177e4c3f41 Linus Torvalds      2005-04-16  5282  				&exception);
^1da177e4c3f41 Linus Torvalds      2005-04-16  5283  	} while (exception.retry);
aa9c2669626ca7 David Quigley       2013-05-22  5284  	nfs4_label_release_security(label);
aa9c2669626ca7 David Quigley       2013-05-22  5285  
4c35d65f4c6f1e Anna Schumaker      2025-05-16  5286  	if (err != 0)
4c35d65f4c6f1e Anna Schumaker      2025-05-16  5287  		return ERR_PTR(err);
8376583b84a193 NeilBrown           2025-02-27  5288  	return alias;
^1da177e4c3f41 Linus Torvalds      2005-04-16  5289  }

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki