From: Stephen Zhang <starzhangzsd@gmail.com>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: tytso@mit.edu, adilger.kernel@dilger.ca, yi.zhang@huawei.com,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
zhangshida@kylinos.cn, stable@kernel.org,
Andreas Dilger <adilger@dilger.ca>
Subject: Re: [PATCH v3] ext4: Fix rec_len verify error
Date: Wed, 2 Aug 2023 09:17:05 +0800 [thread overview]
Message-ID: <CANubcdX2-T1QpDRmvddL-9bme4ZeFvre4N_nsw=gursx9zSQhg@mail.gmail.com> (raw)
In-Reply-To: <20230801151828.GB11332@frogsfrogsfrogs>
Darrick J. Wong <djwong@kernel.org> 于2023年8月1日周二 23:18写道：
>
>
> This is sitll missing some pieces; what about this clause at line 367:
>
> if (t->det_reserved_zero1 ||
> le16_to_cpu(t->det_rec_len) != sizeof(struct ext4_dir_entry_tail) ||
> t->det_reserved_zero2 ||
> t->det_reserved_ft != EXT4_FT_DIR_CSUM)
> return NULL;
>
Yeah...
> > @@ -445,13 +445,13 @@ static struct dx_countlimit *get_dx_countlimit(struct inode *inode,
> > struct ext4_dir_entry *dp;
> > struct dx_root_info *root;
> > int count_offset;
> > + int blocksize = EXT4_BLOCK_SIZE(inode->i_sb);
> >
> > - if (le16_to_cpu(dirent->rec_len) == EXT4_BLOCK_SIZE(inode->i_sb))
> > + if (ext4_rec_len_from_disk(dirent->rec_len, blocksize) == blocksize)
> > count_offset = 8;
> > - else if (le16_to_cpu(dirent->rec_len) == 12) {
> > + else if (ext4_rec_len_from_disk(dirent->rec_len, blocksize) == 12) {
>
> Why not lift this ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ to a
> local variable? @dirent doesn't change, right?
>
Will do.
> > dp = (struct ext4_dir_entry *)(((void *)dirent) + 12);
> > - if (le16_to_cpu(dp->rec_len) !=
> > - EXT4_BLOCK_SIZE(inode->i_sb) - 12)
> > + if (ext4_rec_len_from_disk(dp->rec_len, blocksize) != blocksize - 12)
> > return NULL;
> > root = (struct dx_root_info *)(((void *)dp + 12));
> > if (root->reserved_zero ||
>
> What about dx_make_map?
>
dx_make_map(
....
map_tail->size = le16_to_cpu(de->rec_len);
That might be a questionable one...
map_tail->size is 16 bit, while the key reason we want ext4_rec_len_from_disk
is converting 16-bit rec_len disk form to a in-memory form consisting of like 17
bits...i.e. 0x10000.
Cheers,
Shida
> Here's all the opencoded access I could find:
>
> $ git grep le16.*rec_len fs/ext4/
> fs/ext4/namei.c:356: le16_to_cpu(d->rec_len));
> fs/ext4/namei.c:367: le16_to_cpu(t->det_rec_len) != sizeof(struct ext4_dir_entry_tail) ||
> fs/ext4/namei.c:449: if (le16_to_cpu(dirent->rec_len) == EXT4_BLOCK_SIZE(inode->i_sb))
> fs/ext4/namei.c:451: else if (le16_to_cpu(dirent->rec_len) == 12) {
> fs/ext4/namei.c:453: if (le16_to_cpu(dp->rec_len) !=
> fs/ext4/namei.c:1338: map_tail->size = le16_to_cpu(de->rec_len);
>
> --D
>
> > --
> > 2.27.0
> >
next prev parent reply other threads:[~2023-08-02 1:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-01 11:23 [PATCH v3] ext4: Fix rec_len verify error zhangshida
2023-08-01 15:18 ` Darrick J. Wong
2023-08-02 1:17 ` Stephen Zhang [this message]
2023-08-02 6:07 ` Andreas Dilger
2023-08-03 1:52 ` Stephen Zhang
2023-08-03 3:09 ` Darrick J. Wong
2023-08-03 22:34 ` Andreas Dilger
2023-08-04 2:11 ` Stephen Zhang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CANubcdX2-T1QpDRmvddL-9bme4ZeFvre4N_nsw=gursx9zSQhg@mail.gmail.com' \
--to=starzhangzsd@gmail.com \
--cc=adilger.kernel@dilger.ca \
--cc=adilger@dilger.ca \
--cc=djwong@kernel.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@kernel.org \
--cc=tytso@mit.edu \
--cc=yi.zhang@huawei.com \
--cc=zhangshida@kylinos.cn \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).