[PATCH v4 2/5] exfat: add NameLength check when extracting name

Tetsuhiro Kohada
2020-08-26T11:58:09Z

The current implementation doesn't care NameLength when extracting
the name from Name dir-entries, so the name may be incorrect.
(Without null-termination, Insufficient Name dir-entry, etc)
Add a NameLength check when extracting the name from Name dir-entries
to extract correct name.
And, change to get the information of file/stream-ext dir-entries
via the member variable of exfat_entry_set_cache.

Signed-off-by: Tetsuhiro Kohada <kohada.t2@gmail.com>
---
Changes in v2
- Add error check when extracting name
- Change error from EIO to EINVAL when the name length is invalid
- Correct the spelling in commit messages
Changes in v3:
- Nothing
Changes in v4:
- Into patch series '[PATCH v4] exfat: integrates dir-entry getting and validation'

fs/exfat/dir.c | 87 +++++++++++++++++++++++++-------------------------
1 file changed, 43 insertions(+), 44 deletions(-)

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index bb3c20bac422..99d9e6d119d6 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -28,16 +28,15 @@ static int exfat_extract_uni_name(struct exfat_dentry *ep,

}

-static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
- struct exfat_chain *p_dir, int entry, unsigned short *uniname)
+static int exfat_get_uniname_from_name_entries(struct exfat_entry_set_cache *es,
+ struct exfat_uni_name *uniname)
{
- int i;
- struct exfat_entry_set_cache *es;
+ int n, l, i;
struct exfat_dentry *ep;

- es = exfat_get_dentry_set(sb, p_dir, entry, ES_ALL_ENTRIES);
- if (!es)
- return;
+ uniname->name_len = ES_STREAM(es).name_len;
+ if (uniname->name_len == 0)
+ return -EINVAL;

/*
* First entry : file entry
@@ -45,24 +44,26 @@ static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
* Third entry : first file-name entry
* So, the index of first file-name dentry should start from 2.
*/
-
- i = ES_INDEX_NAME;
- while ((ep = exfat_get_validated_dentry(es, i++, TYPE_NAME))) {
- exfat_extract_uni_name(ep, uniname);
- uniname += EXFAT_FILE_NAME_LEN;
+ for (l = 0, n = ES_INDEX_NAME; l < uniname->name_len; n++) {
+ ep = exfat_get_validated_dentry(es, n, TYPE_NAME);
+ if (!ep)
+ return -EIO;
+ for (i = 0; l < uniname->name_len && i < EXFAT_FILE_NAME_LEN; i++, l++)
+ uniname->name[l] = le16_to_cpu(ep->dentry.name.unicode_0_14[i]);
}
-
- exfat_free_dentry_set(es, false);
+ uniname->name[l] = 0;
+ return 0;
}

/* read a directory entry from the opened directory */
static int exfat_readdir(struct inode *inode, struct exfat_dir_entry *dir_entry)
{
- int i, dentries_per_clu, dentries_per_clu_bits = 0;
+ int i, dentries_per_clu, dentries_per_clu_bits = 0, err;
unsigned int type, clu_offset;
sector_t sector;
struct exfat_chain dir, clu;
struct exfat_uni_name uni_name;
+ struct exfat_entry_set_cache *es;
struct exfat_dentry *ep;
struct super_block *sb = inode->i_sb;
struct exfat_sb_info *sbi = EXFAT_SB(sb);
@@ -114,47 +115,45 @@ static int exfat_readdir(struct inode *inode, struct exfat_dir_entry *dir_entry)
return -EIO;

type = exfat_get_entry_type(ep);
- if (type == TYPE_UNUSED) {
- brelse(bh);
+ brelse(bh);
+
+ if (type == TYPE_UNUSED)
break;
- }

- if (type != TYPE_FILE && type != TYPE_DIR) {
- brelse(bh);
+ if (type != TYPE_FILE && type != TYPE_DIR)
continue;
- }

- dir_entry->attr = le16_to_cpu(ep->dentry.file.attr);
+ es = exfat_get_dentry_set(sb, &dir, dentry, ES_ALL_ENTRIES);
+ if (!es)
+ return -EIO;
+
+ dir_entry->attr = le16_to_cpu(ES_FILE(es).attr);
exfat_get_entry_time(sbi, &dir_entry->crtime,
- ep->dentry.file.create_tz,
- ep->dentry.file.create_time,
- ep->dentry.file.create_date,
- ep->dentry.file.create_time_cs);
+ ES_FILE(es).create_tz,
+ ES_FILE(es).create_time,
+ ES_FILE(es).create_date,
+ ES_FILE(es).create_time_cs);
exfat_get_entry_time(sbi, &dir_entry->mtime,
- ep->dentry.file.modify_tz,
- ep->dentry.file.modify_time,
- ep->dentry.file.modify_date,
- ep->dentry.file.modify_time_cs);
+ ES_FILE(es).modify_tz,
+ ES_FILE(es).modify_time,
+ ES_FILE(es).modify_date,
+ ES_FILE(es).modify_time_cs);
exfat_get_entry_time(sbi, &dir_entry->atime,
- ep->dentry.file.access_tz,
- ep->dentry.file.access_time,
- ep->dentry.file.access_date,
+ ES_FILE(es).access_tz,
+ ES_FILE(es).access_time,
+ ES_FILE(es).access_date,
0);

- *uni_name.name = 0x0;
- exfat_get_uniname_from_ext_entry(sb, &dir, dentry,
- uni_name.name);
+ dir_entry->size = le64_to_cpu(ES_STREAM(es).valid_size);
+
+ err = exfat_get_uniname_from_name_entries(es, &uni_name);
+ exfat_free_dentry_set(es, false);
+ if (err)
+ return err;
+
exfat_utf16_to_nls(sb, &uni_name,
dir_entry->namebuf.lfn,
dir_entry->namebuf.lfnbuf_len);
- brelse(bh);
-
- ep = exfat_get_dentry(sb, &clu, i + 1, &bh, NULL);
- if (!ep)
- return -EIO;
- dir_entry->size =
- le64_to_cpu(ep->dentry.stream.valid_size);
- brelse(bh);

ei->hint_bmap.off = dentry >> dentries_per_clu_bits;
ei->hint_bmap.clu = clu.dir;
--
2.25.1