linux-ext4 - Re: [PATCH v2] ext4: avoid eh_entries overflow before insert extent

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Date:	Thu, 23 Jun 2011 17:00:38 +0800
From:	Yongqiang Yang <xiaoqiangnk@...il.com>
To:	Robin Dong <hao.bigrat@...il.com>
Cc:	linux-ext4@...r.kernel.org, Robin Dong <sanbai@...bao.com>
Subject: Re: [PATCH v2] ext4: avoid eh_entries overflow before insert extent_idx

On Thu, Jun 23, 2011 at 4:47 PM, Robin Dong <hao.bigrat@...il.com> wrote:
> If eh_entries is equal to (or greater than) eh_max, the operation of
> inserting new extent_idx will make number of entries overflow.
> So check eh_entries before inserting the new extent_idx.
>
> Signed-off-by: Robin Dong <sanbai@...bao.com>
> ---
>  fs/ext4/extents.c |   18 ++++++++++--------
>  1 files changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index eb63c7b..792e77e 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -776,6 +776,16 @@ static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
>                                 logical, le32_to_cpu(curp->p_idx->ei_block));
>                return -EIO;
>        }
> +
> +       if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
> +                            >= le16_to_cpu(curp->p_hdr->eh_max))) {
> +               EXT4_ERROR_INODE(inode,
> +                                "eh_entries %d >= eh_max %d!",
> +                                le16_to_cpu(curp->p_hdr->eh_entries),
> +                                le16_to_cpu(curp->p_hdr->eh_max));
> +               return -EIO;
> +       }
> +
>        len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;
>        if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
>                /* insert after */
> @@ -805,14 +815,6 @@ static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
>        ext4_idx_store_pblock(ix, ptr);
>        le16_add_cpu(&curp->p_hdr->eh_entries, 1);
>
> -       if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
> -                            > le16_to_cpu(curp->p_hdr->eh_max))) {
> -               EXT4_ERROR_INODE(inode,
> -                                "eh_entries %d > eh_max %d!",
> -                                le16_to_cpu(curp->p_hdr->eh_entries),
> -                                le16_to_cpu(curp->p_hdr->eh_max));
> -               return -EIO;
> -       }
>        if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
condition ix > EXT_LAST_INDEX(curp->p_hdr) can not be true.  Right?
May be we can remove this if-statement in this patch.

Yongqiang.
>                EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
>                return -EIO;
> --
> 1.7.1
>
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-- 
Best Wishes
Yongqiang Yang
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