linux.git/fs/exfat, branch v6.13

exfat: fix the infinite loop in __exfat_free_cluster()

2024-12-31T08:51:21+00:00

In __exfat_free_cluster(), the cluster chain is traversed until the
EOF cluster. If the cluster chain includes a loop due to file system
corruption, the EOF cluster cannot be traversed, resulting in an
infinite loop.

This commit uses the total number of clusters to prevent this infinite
loop.

Reported-by: syzbot+1de5a37cb85a2d536330@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1de5a37cb85a2d536330
Tested-by: syzbot+1de5a37cb85a2d536330@syzkaller.appspotmail.com
Fixes: 31023864e67a ("exfat: add fat entry operations")
Signed-off-by: Yuezhang Mo 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: fix the new buffer was not zeroed before writing

2024-12-31T08:51:16+00:00

Before writing, if a buffer_head marked as new, its data must
be zeroed, otherwise uninitialized data in the page cache will
be written.

So this commit uses folio_zero_new_buffers() to zero the new
buffers before ->write_end().

Fixes: 6630ea49103c ("exfat: move extend valid_size into ->page_mkwrite()")
Reported-by: syzbot+91ae49e1c1a2634d20c0@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=91ae49e1c1a2634d20c0
Tested-by: syzbot+91ae49e1c1a2634d20c0@syzkaller.appspotmail.com
Signed-off-by: Yuezhang Mo 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: fix the infinite loop in exfat_readdir()

2024-12-31T08:49:40+00:00

If the file system is corrupted so that a cluster is linked to
itself in the cluster chain, and there is an unused directory
entry in the cluster, 'dentry' will not be incremented, causing
condition 'dentry < max_dentries' unable to prevent an infinite
loop.

This infinite loop causes s_lock not to be released, and other
tasks will hang, such as exfat_sync_fs().

This commit stops traversing the cluster chain when there is unused
directory entry in the cluster to avoid this infinite loop.

Reported-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=205c2644abdff9d3f9fc
Tested-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com
Fixes: ca06197382bd ("exfat: add directory operations")
Signed-off-by: Yuezhang Mo 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

exfat: fix exfat_find_empty_entry() not returning error on failure

2024-12-17T11:21:59+00:00

On failure, "dentry" is the error code. If the error code indicates
that there is no space, a new cluster may need to be allocated; for
other errors, it should be returned directly.

Only on success, "dentry" is the index of the directory entry, and
it needs to be converted into the directory entry index within the
cluster where it is located.

Fixes: 8a3f5711ad74 ("exfat: reduce FAT chain traversal")
Reported-by: syzbot+6f6c9397e0078ef60bce@syzkaller.appspotmail.com
Tested-by: syzbot+6f6c9397e0078ef60bce@syzkaller.appspotmail.com
Signed-off-by: Yuezhang Mo 
Reviewed-by: Sungjong Seo 
Signed-off-by: Namjae Jeon

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