fs/ntfs/attrlist.c:126 ntfs_attrlist_entry_add() warn: variable dereferenced before check 'ni' (see line 122)

fs/ntfs/attrlist.c:126 ntfs_attrlist_entry_add() warn: variable dereferenced before check 'ni' (see line 122)

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   26fd6bff2c050196005312d1d306889220952a99
commit: 47503f989736d6c4c9f8bfca1c28d267473ccd4b ntfs: add Kconfig and Makefile
config: x86_64-randconfig-161-20260501 (https://download.01.org/0day-ci/archive/20260501/202605011540.0FJWFGIn-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
smatch: v0.5.0-9065-ge9cc34fd

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
| Fixes: 47503f989736 ("ntfs: add Kconfig and Makefile")
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202605011540.0FJWFGIn-lkp@intel.com/

New smatch warnings:
fs/ntfs/attrlist.c:126 ntfs_attrlist_entry_add() warn: variable dereferenced before check 'ni' (see line 122)
fs/ntfs/attrlist.c:126 ntfs_attrlist_entry_add() warn: variable dereferenced before check 'attr' (see line 122)
fs/ntfs/attrib.c:2807 ntfs_attr_open() warn: variable dereferenced before check 'ni' (see line 2804)

Old smatch warnings:
fs/ntfs/attrib.c:2115 ntfs_resident_attr_record_add() warn: variable dereferenced before check 'ni' (see line 2111)
fs/ntfs/attrib.c:2237 ntfs_non_resident_attr_record_add() warn: variable dereferenced before check 'ni' (see line 2232)
fs/ntfs/attrib.c:4951 ntfs_attr_remove() warn: variable dereferenced before check 'ni' (see line 4950)

vim +/ni +126 fs/ntfs/attrlist.c

495e90fa334828d Namjae Jeon 2026-02-13  112  int ntfs_attrlist_entry_add(struct ntfs_inode *ni, struct attr_record *attr)
495e90fa334828d Namjae Jeon 2026-02-13  113  {
495e90fa334828d Namjae Jeon 2026-02-13  114  	struct attr_list_entry *ale;
495e90fa334828d Namjae Jeon 2026-02-13  115  	__le64 mref;
495e90fa334828d Namjae Jeon 2026-02-13  116  	struct ntfs_attr_search_ctx *ctx;
495e90fa334828d Namjae Jeon 2026-02-13  117  	u8 *new_al;
495e90fa334828d Namjae Jeon 2026-02-13  118  	int entry_len, entry_offset, err;
495e90fa334828d Namjae Jeon 2026-02-13  119  	struct mft_record *ni_mrec;
495e90fa334828d Namjae Jeon 2026-02-13  120  	u8 *old_al;
495e90fa334828d Namjae Jeon 2026-02-13  121  
495e90fa334828d Namjae Jeon 2026-02-13 @122  	ntfs_debug("Entering for inode 0x%llx, attr 0x%x.\n",
495e90fa334828d Namjae Jeon 2026-02-13  123  			(long long) ni->mft_no,
                                                                            ^^^^^^^^^^
495e90fa334828d Namjae Jeon 2026-02-13  124  			(unsigned int) le32_to_cpu(attr->type));
495e90fa334828d Namjae Jeon 2026-02-13  125  
495e90fa334828d Namjae Jeon 2026-02-13 @126  	if (!ni || !attr) {
                                                    ^^^
Checked too late.

495e90fa334828d Namjae Jeon 2026-02-13  127  		ntfs_debug("Invalid arguments.\n");
495e90fa334828d Namjae Jeon 2026-02-13  128  		return -EINVAL;
495e90fa334828d Namjae Jeon 2026-02-13  129  	}
495e90fa334828d Namjae Jeon 2026-02-13  130  
495e90fa334828d Namjae Jeon 2026-02-13  131  	ni_mrec = map_mft_record(ni);
495e90fa334828d Namjae Jeon 2026-02-13  132  	if (IS_ERR(ni_mrec)) {
495e90fa334828d Namjae Jeon 2026-02-13  133  		ntfs_debug("Invalid arguments.\n");
495e90fa334828d Namjae Jeon 2026-02-13  134  		return -EIO;
495e90fa334828d Namjae Jeon 2026-02-13  135  	}
495e90fa334828d Namjae Jeon 2026-02-13  136  
495e90fa334828d Namjae Jeon 2026-02-13  137  	mref = MK_LE_MREF(ni->mft_no, le16_to_cpu(ni_mrec->sequence_number));
495e90fa334828d Namjae Jeon 2026-02-13  138  	unmap_mft_record(ni);
495e90fa334828d Namjae Jeon 2026-02-13  139  
495e90fa334828d Namjae Jeon 2026-02-13  140  	if (ni->nr_extents == -1)

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

Re: fs/ntfs/attrlist.c:126 ntfs_attrlist_entry_add() warn: variable dereferenced before check 'ni' (see line 122)

[Namjae Jeon]

On Fri, May 1, 2026 at 6:12 PM Dan Carpenter <error27@gmail.com> wrote:
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   26fd6bff2c050196005312d1d306889220952a99
> commit: 47503f989736d6c4c9f8bfca1c28d267473ccd4b ntfs: add Kconfig and Makefile
> config: x86_64-randconfig-161-20260501 (https://download.01.org/0day-ci/archive/20260501/202605011540.0FJWFGIn-lkp@intel.com/config)
> compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
> smatch: v0.5.0-9065-ge9cc34fd
>
> 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
> | Fixes: 47503f989736 ("ntfs: add Kconfig and Makefile")
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <error27@gmail.com>
> | Closes: https://lore.kernel.org/r/202605011540.0FJWFGIn-lkp@intel.com/
>
> New smatch warnings:
> fs/ntfs/attrlist.c:126 ntfs_attrlist_entry_add() warn: variable dereferenced before check 'ni' (see line 122)
> fs/ntfs/attrlist.c:126 ntfs_attrlist_entry_add() warn: variable dereferenced before check 'attr' (see line 122)
> fs/ntfs/attrib.c:2807 ntfs_attr_open() warn: variable dereferenced before check 'ni' (see line 2804)
>
> Old smatch warnings:
> fs/ntfs/attrib.c:2115 ntfs_resident_attr_record_add() warn: variable dereferenced before check 'ni' (see line 2111)
> fs/ntfs/attrib.c:2237 ntfs_non_resident_attr_record_add() warn: variable dereferenced before check 'ni' (see line 2232)
> fs/ntfs/attrib.c:4951 ntfs_attr_remove() warn: variable dereferenced before check 'ni' (see line 4950)
I will fix it.
Thanks for the report!