linux-kernel - Re: [PATCH] fs/ntfs3: Validate attribute data and valid sizes

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Message-ID: <1ddcbb4a-ce49-a4a1-f8c2-a2896f3b2451@paragon-software.com>
Date:   Sat, 12 Nov 2022 21:09:40 +0300
From:   Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
To:     Abdun Nihaal <abdun.nihaal@...il.com>
CC:     <ntfs3@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
        <skhan@...uxfoundation.org>,
        <linux-kernel-mentees@...ts.linuxfoundation.org>,
        <syzbot+fa4648a5446460b7b963@...kaller.appspotmail.com>
Subject: Re: [PATCH] fs/ntfs3: Validate attribute data and valid sizes



On 10/4/22 06:15, Abdun Nihaal wrote:
> The data_size and valid_size fields of non resident attributes should be
> less than the its alloc_size field, but this is not checked in
> ntfs_read_mft function.
> 
> Syzbot reports a allocation order warning due to a large unchecked value
> of data_size getting assigned to inode->i_size which is then passed to
> kcalloc.
> 
> Add sanity check for ensuring that the data_size and valid_size fields
> are not larger than alloc_size field.
> 
> Link: https://syzkaller.appspot.com/bug?extid=fa4648a5446460b7b963
> Reported-and-tested-by: syzbot+fa4648a5446460b7b963@...kaller.appspotmail.com
> Fixes: (82cae269cfa95) fs/ntfs3: Add initialization of super block
> Signed-off-by: Abdun Nihaal <abdun.nihaal@...il.com>
> ---
>   fs/ntfs3/inode.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
> index e9cf00d14733..9c244029be75 100644
> --- a/fs/ntfs3/inode.c
> +++ b/fs/ntfs3/inode.c
> @@ -132,6 +132,13 @@ static struct inode *ntfs_read_mft(struct inode *inode,
>   	if (le16_to_cpu(attr->name_off) + attr->name_len > asize)
>   		goto out;
>   
> +	if (attr->non_res) {
> +		t64 = le64_to_cpu(attr->nres.alloc_size);
> +		if (le64_to_cpu(attr->nres.data_size) > t64 ||
> +		    le64_to_cpu(attr->nres.valid_size) > t64)
> +			goto out;
> +	}
> +
>   	switch (attr->type) {
>   	case ATTR_STD:
>   		if (attr->non_res ||

Applied, thanks again for patch!