Re: [PATCH 1/2] exfat: add NameLength check when extracting name

Tetsuhiro Kohada
2020-08-12T04:53:20Z

Thanks for your reply.

On 2020/08/09 1:54, Sungjong Seo wrote:
>> 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.
>>
>> ** This patch depends on:
>> '[PATCH v3] exfat: integrates dir-entry getting and validation'.
>>
>> Signed-off-by: Tetsuhiro Kohada <kohada.t2@gmail.com>
>> ---
>> fs/exfat/dir.c | 81 ++++++++++++++++++++++++--------------------------
>> 1 file changed, 39 insertions(+), 42 deletions(-)
>>
>> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index
>> 91cdbede0fd1..545bb73b95e9 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->de_stream->name_len;
>> + if (uniname->name_len == 0)
>> + return -EIO;
>
> -EINVAL looks better.

OK.
I'll change in v2.

>> /*
>> * First entry : file entry
>> @@ -45,14 +44,15 @@ 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 = 2;
>> - 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 = 2; 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]);
>
> Looks good.
>
>> }
>> -
>> - exfat_free_dentry_set(es, false);
>> + uniname->name[l] = 0;
>> + return 0;
>> }
>>
>> /* read a directory entry from the opened directory */ @@ -63,6 +63,7 @@
>> static int exfat_readdir(struct inode *inode, struct exfat_dir_entry
>> *dir_entry)
> [snip]
>> - *uni_name.name = 0x0;
>> - exfat_get_uniname_from_ext_entry(sb, &dir, dentry,
>> - uni_name.name);
>> + dir_entry->size = le64_to_cpu(es->de_stream-
>>> valid_size);
>> +
>> + exfat_get_uniname_from_name_entries(es, &uni_name);
>
> Modified function has a return value.
> It would be better to check the return value.

Oops!
I'll fix it in v2.

>> 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);
>> + exfat_free_dentry_set(es, false);
>>
>> ei->hint_bmap.off = dentry >> dentries_per_clu_bits;
>> ei->hint_bmap.clu = clu.dir;
>> --
>> 2.25.1
>
>