Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Andreas Dilger <adilger@dilger.ca>
Message-Id: <30B88888-4652-45B9-974F-C06468D30AD5@dilger.ca>
Content-Type: multipart/signed;
 boundary="Apple-Mail=_BCBD2BCA-DFEC-4788-AC3F-A884CD878BEB";
 protocol="application/pgp-signature"; micalg=pgp-sha256
Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\))
Subject: Re: [PATCH v4] ext4: Fix rec_len verify error
Date:   Thu, 3 Aug 2023 16:31:59 -0600
In-Reply-To: <20230803060938.1929759-1-zhangshida@kylinos.cn>
Cc:     Theodore Ts'o <tytso@mit.edu>, Zhang Yi <yi.zhang@huawei.com>,
        "Darrick J. Wong" <djwong@kernel.org>,
        Ext4 Developers List <linux-ext4@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        zhangshida@kylinos.cn, stable@kernel.org
To:     zhangshida <starzhangzsd@gmail.com>
References: <20230803060938.1929759-1-zhangshida@kylinos.cn>
Precedence: bulk


--Apple-Mail=_BCBD2BCA-DFEC-4788-AC3F-A884CD878BEB
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=us-ascii

On Aug 3, 2023, at 12:09 AM, zhangshida <starzhangzsd@gmail.com> wrote:
>=20
> From: Shida Zhang <zhangshida@kylinos.cn>
>=20
> With the configuration PAGE_SIZE 64k and filesystem blocksize 64k,
> a problem occurred when more than 13 million files were directly =
created
> under a directory:
>=20
> EXT4-fs error (device xx): ext4_dx_csum_set:492: inode #xxxx: comm =
xxxxx: dir seems corrupt?  Run e2fsck -D.
> EXT4-fs error (device xx): ext4_dx_csum_verify:463: inode #xxxx: comm =
xxxxx: dir seems corrupt?  Run e2fsck -D.
> EXT4-fs error (device xx): dx_probe:856: inode #xxxx: block 8188: comm =
xxxxx: Directory index failed checksum
>=20
> When enough files are created, the fake_dirent->reclen will be 0xffff.
> it doesn't equal to the blocksize 65536, i.e. 0x10000.
>=20
> But it is not the same condition when blocksize equals to 4k.
> when enough files are created, the fake_dirent->reclen will be 0x1000.
> it equals to the blocksize 4k, i.e. 0x1000.
>=20
> The problem seems to be related to the limitation of the 16-bit field
> when the blocksize is set to 64k.
> To address this, helpers like ext4_rec_len_{from,to}_disk has already
> been introduced to complete the conversion between the encoded and the
> plain form of rec_len.
>=20
> So fix this one by using the helper, and all the other in this file =
too.
>=20
> Cc: stable@kernel.org
> Fixes: dbe89444042a ("ext4: Calculate and verify checksums for htree =
nodes")
> Suggested-by: Andreas Dilger <adilger@dilger.ca>
> Suggested-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>

Thanks for the updated patch.  You can add:

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> ---
> v3->v4:
> 1,Convert all the other rec_len, litrerally.
> 2,Lift a helper output to a local variable.
> --Suggested by Darrick.
> v2->v3:
> 1,Convert all the other rec_len if necessary, as suggested by Darrick.
> 2,Rephrase the commit message.
> v1->v2:
> Use the existing helper to covert the rec_len, as suggested by =
Andreas.
>=20
> fs/ext4/namei.c | 26 +++++++++++++++-----------
> 1 file changed, 15 insertions(+), 11 deletions(-)
>=20
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 0caf6c730ce3..34fb2d1e66aa 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -343,17 +343,17 @@ static struct ext4_dir_entry_tail =
*get_dirent_tail(struct inode *inode,
> 						   struct buffer_head =
*bh)
> {
> 	struct ext4_dir_entry_tail *t;
> +	int blocksize =3D EXT4_BLOCK_SIZE(inode->i_sb);
>=20
> #ifdef PARANOID
> 	struct ext4_dir_entry *d, *top;
>=20
> 	d =3D (struct ext4_dir_entry *)bh->b_data;
> 	top =3D (struct ext4_dir_entry *)(bh->b_data +
> -		(EXT4_BLOCK_SIZE(inode->i_sb) -
> -		 sizeof(struct ext4_dir_entry_tail)));
> -	while (d < top && d->rec_len)
> +		(blocksize - sizeof(struct ext4_dir_entry_tail)));
> +	while (d < top && ext4_rec_len_from_disk(d->rec_len, blocksize))
> 		d =3D (struct ext4_dir_entry *)(((void *)d) +
> -		    le16_to_cpu(d->rec_len));
> +		    ext4_rec_len_from_disk(d->rec_len, blocksize));
>=20
> 	if (d !=3D top)
> 		return NULL;
> @@ -364,7 +364,8 @@ static struct ext4_dir_entry_tail =
*get_dirent_tail(struct inode *inode,
> #endif
>=20
> 	if (t->det_reserved_zero1 ||
> -	    le16_to_cpu(t->det_rec_len) !=3D sizeof(struct =
ext4_dir_entry_tail) ||
> +	    (ext4_rec_len_from_disk(t->det_rec_len, blocksize) !=3D
> +	     sizeof(struct ext4_dir_entry_tail)) ||
> 	    t->det_reserved_zero2 ||
> 	    t->det_reserved_ft !=3D EXT4_FT_DIR_CSUM)
> 		return NULL;
> @@ -445,13 +446,14 @@ 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 =3D EXT4_BLOCK_SIZE(inode->i_sb);
> +	unsigned int rlen =3D ext4_rec_len_from_disk(dirent->rec_len, =
blocksize);
>=20
> -	if (le16_to_cpu(dirent->rec_len) =3D=3D =
EXT4_BLOCK_SIZE(inode->i_sb))
> +	if (rlen =3D=3D blocksize)
> 		count_offset =3D 8;
> -	else if (le16_to_cpu(dirent->rec_len) =3D=3D 12) {
> +	else if (rlen =3D=3D 12) {
> 		dp =3D (struct ext4_dir_entry *)(((void *)dirent) + 12);
> -		if (le16_to_cpu(dp->rec_len) !=3D
> -		    EXT4_BLOCK_SIZE(inode->i_sb) - 12)
> +		if (ext4_rec_len_from_disk(dp->rec_len, blocksize) !=3D =
blocksize - 12)
> 			return NULL;
> 		root =3D (struct dx_root_info *)(((void *)dp + 12));
> 		if (root->reserved_zero ||
> @@ -1315,6 +1317,7 @@ static int dx_make_map(struct inode *dir, struct =
buffer_head *bh,
> 	unsigned int buflen =3D bh->b_size;
> 	char *base =3D bh->b_data;
> 	struct dx_hash_info h =3D *hinfo;
> +	int blocksize =3D EXT4_BLOCK_SIZE(dir->i_sb);
>=20
> 	if (ext4_has_metadata_csum(dir->i_sb))
> 		buflen -=3D sizeof(struct ext4_dir_entry_tail);
> @@ -1335,11 +1338,12 @@ static int dx_make_map(struct inode *dir, =
struct buffer_head *bh,
> 			map_tail--;
> 			map_tail->hash =3D h.hash;
> 			map_tail->offs =3D ((char *) de - base)>>2;
> -			map_tail->size =3D le16_to_cpu(de->rec_len);
> +			map_tail->size =3D =
ext4_rec_len_from_disk(de->rec_len,
> +								=
blocksize);
> 			count++;
> 			cond_resched();
> 		}
> -		de =3D ext4_next_entry(de, dir->i_sb->s_blocksize);
> +		de =3D ext4_next_entry(de, blocksize);
> 	}
> 	return count;
> }
> --
> 2.27.0
>=20


Cheers, Andreas


--Apple-Mail=_BCBD2BCA-DFEC-4788-AC3F-A884CD878BEB
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
	filename=signature.asc
Content-Type: application/pgp-signature;
	name=signature.asc
Content-Description: Message signed with OpenPGP

-----BEGIN PGP SIGNATURE-----
Comment: GPGTools - http://gpgtools.org
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=ynvs
-----END PGP SIGNATURE-----

--Apple-Mail=_BCBD2BCA-DFEC-4788-AC3F-A884CD878BEB--