Re: [PATCH next 2/3] debugfs: introduce debugfs_create_single[,_data]

[Dan Carpenter]

[ How do I fetch 0day git branchs?
  git fetch https://github.com/0day-ci/linux/commits/Kefeng-Wang/debugfs-introduce-debugfs_create_single-seq-_data/20191129-173440
  doesn't work. - dan ]

Hi Kefeng,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on next-20191128]
[cannot apply to v5.4]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Kefeng-Wang/debugfs-introduce-debugfs_create_single-seq-_data/20191129-173440
base:    d26b0e226f222c22c3b7e9d16e5b886e7c51057a


If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

New smatch warnings:
fs/debugfs/file.c:1193 debugfs_create_single_data() warn: overwrite may leak 'entry'

Old smatch warnings:
include/linux/compiler.h:247 __write_once_size() warn: potential memory corrupting cast 8 vs 4 bytes

# https://github.com/0day-ci/linux/commit/198a4ea9768d6790a169e8b802e702c208aafbd1
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 198a4ea9768d6790a169e8b802e702c208aafbd1
vim +/entry +1193 fs/debugfs/file.c

198a4ea9768d67 Kefeng Wang      2019-11-29  1179  struct dentry *debugfs_create_single_data(const char *name, umode_t mode,
198a4ea9768d67 Kefeng Wang      2019-11-29  1180  					  struct dentry *parent, void *data,
198a4ea9768d67 Kefeng Wang      2019-11-29  1181  					  int (*read_fn)(struct seq_file *s,
198a4ea9768d67 Kefeng Wang      2019-11-29  1182  							 void *data))
198a4ea9768d67 Kefeng Wang      2019-11-29  1183  {
198a4ea9768d67 Kefeng Wang      2019-11-29  1184  	struct debugfs_entry *entry;
198a4ea9768d67 Kefeng Wang      2019-11-29  1185  
198a4ea9768d67 Kefeng Wang      2019-11-29  1186  	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
198a4ea9768d67 Kefeng Wang      2019-11-29  1187  	if (!entry)
198a4ea9768d67 Kefeng Wang      2019-11-29  1188  		return ERR_PTR(-ENOMEM);
198a4ea9768d67 Kefeng Wang      2019-11-29  1189  
198a4ea9768d67 Kefeng Wang      2019-11-29  1190  	entry->read = read_fn;
198a4ea9768d67 Kefeng Wang      2019-11-29  1191  	entry->data = data;
198a4ea9768d67 Kefeng Wang      2019-11-29  1192  
198a4ea9768d67 Kefeng Wang      2019-11-29 @1193  	entry = debugfs_set_lowest_bit(entry);
                                                        ^^^^^^^^
I haven't looked at the surrounding code but how would we free "entry"
when we write over it here?

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