linux.git/fs/exfat, branch vsnprintf

exfat: reduce FAT chain traversal

2024-11-25T08:08:27+00:00

Before this commit, ->dir and ->entry of exfat_inode_info record the
first cluster of the parent directory and the directory entry index
starting from this cluster.

The directory entry set will be gotten during write-back-inode/rmdir/
unlink/rename. If the clusters of the parent directory are not
continuous, the FAT chain will be traversed from the first cluster of
the parent directory to find the cluster where ->entry is located.

After this commit, ->dir records the cluster where the first directory
entry in the directory entry set is located, and ->entry records the
directory entry index in the cluster, so that there is almost no need
to access the FAT when getting the directory entry set.

Signed-off-by: Yuezhang Mo 
Reviewed-by: Aoyama Wataru 
Reviewed-by: Daniel Palmer 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: code cleanup for exfat_readdir()

2024-11-25T08:08:26+00:00

For the root directory and other directories, the clusters
allocated to them can be obtained from exfat_inode_info, and
there is no need to distinguish them.

And there is no need to initialize atime/ctime/mtime/size in
exfat_readdir(), because exfat_iterate() does not use them.

Signed-off-by: Yuezhang Mo 
Reviewed-by: Aoyama Wataru 
Reviewed-by: Daniel Palmer 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: remove argument 'p_dir' from exfat_add_entry()

2024-11-25T08:08:25+00:00

The output of argument 'p_dir' of exfat_add_entry() is not used
in either exfat_mkdir() or exfat_create(), remove the argument.

Code refinement, no functional changes.

Signed-off-by: Yuezhang Mo 
Reviewed-by: Aoyama Wataru 
Reviewed-by: Daniel Palmer 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: move exfat_chain_set() out of __exfat_resolve_path()

2024-11-25T08:08:24+00:00

__exfat_resolve_path() mixes two functions. The first one is to
resolve and check if the path is valid. The second one is to output
the cluster assigned to the directory.

The second one is only needed when need to traverse the directory
entries, and calling exfat_chain_set() so early causes p_dir to be
passed as an argument multiple times, increasing the complexity of
the code.

This commit moves the call to exfat_chain_set() before traversing
directory entries.

Signed-off-by: Yuezhang Mo 
Reviewed-by: Aoyama Wataru 
Reviewed-by: Daniel Palmer 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: add exfat_get_dentry_set_by_ei() helper

2024-11-25T08:08:23+00:00

This helper gets the directory entry set of the file for the exfat
inode which has been created.

It's used to remove all the instances of the pattern it replaces
making the code cleaner, it's also a preparation for changing ->dir
to record the cluster where the directory entry set is located and
changing ->entry to record the index of the directory entry within
the cluster.

Signed-off-by: Yuezhang Mo 
Reviewed-by: Aoyama Wataru 
Reviewed-by: Daniel Palmer 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: rename argument name for exfat_move_file and exfat_rename_file

2024-11-25T08:08:21+00:00

In this exfat implementation, the relationship between inode and ei
is ei=EXFAT_I(inode). However, in the arguments of exfat_move_file()
and exfat_rename_file(), argument 'inode' indicates the parent
directory, but argument 'ei' indicates the target file to be renamed.
They do not have the above relationship, which is not friendly to code
readers.

So this commit renames 'inode' to 'parent_inode', making the argument
name match its role.

Signed-off-by: Yuezhang Mo 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: remove unnecessary read entry in __exfat_rename()

2024-11-25T08:08:21+00:00

To determine whether it is a directory, there is no need to read its
directory entry, just use S_ISDIR(inode->i_mode).

Signed-off-by: Yuezhang Mo 
Reviewed-by: Aoyama Wataru 
Reviewed-by: Daniel Palmer 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: fix file being changed by unaligned direct write

2024-11-25T08:08:21+00:00

Unaligned direct writes are invalid and should return an error
without making any changes, rather than extending ->valid_size
and then returning an error. Therefore, alignment checking is
required before extending ->valid_size.

Fixes: 11a347fb6cef ("exfat: change to get file size from DataLength")
Signed-off-by: Yuezhang Mo 
Co-developed-by: Namjae Jeon 
Signed-off-by: Namjae Jeon

exfat: fix uninit-value in __exfat_get_dentry_set

2024-11-25T08:08:21+00:00

There is no check if stream size and start_clu are invalid.
If start_clu is EOF cluster and stream size is 4096, It will
cause uninit value access. because ei->hint_femp.eidx could
be 128(if cluster size is 4K) and wrong hint will allocate
next cluster. and this cluster will be same with the cluster
that is allocated by exfat_extend_valid_size(). The previous
patch will check invalid start_clu, but for clarity, initialize
hint_femp.eidx to zero.

Cc: stable@vger.kernel.org
Reported-by: syzbot+01218003be74b5e1213a@syzkaller.appspotmail.com
Tested-by: syzbot+01218003be74b5e1213a@syzkaller.appspotmail.com
Reviewed-by: Yuezhang Mo 
Signed-off-by: Namjae Jeon

exfat: fix out-of-bounds access of directory entries

2024-11-25T08:08:20+00:00

In the case of the directory size is greater than or equal to
the cluster size, if start_clu becomes an EOF cluster(an invalid
cluster) due to file system corruption, then the directory entry
where ei->hint_femp.eidx hint is outside the directory, resulting
in an out-of-bounds access, which may cause further file system
corruption.

This commit adds a check for start_clu, if it is an invalid cluster,
the file or directory will be treated as empty.

Cc: stable@vger.kernel.org
Signed-off-by: Yuezhang Mo 
Co-developed-by: Namjae Jeon 
Signed-off-by: Namjae Jeon