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From:   Anton Altaparmakov <anton@tuxera.com>
To:     Andrew Morton <akpm@linux-foundation.org>
CC:     "linux-ntfs-dev@lists.sourceforge.net" 
        <linux-ntfs-dev@lists.sourceforge.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        Rustam Kovhaev <rkovhaev@gmail.com>
Subject: Re: [PATCH] ntfs: check for valid standard information attribute
Thread-Topic: [PATCH] ntfs: check for valid standard information attribute
Thread-Index: AQHXBUX43Bx0ygm+wEC4t5YdRoTv2qpemD8A
Date:   Fri, 19 Feb 2021 01:54:30 +0000
Message-ID: <42B686E5-92C1-4AD3-8CF4-E9AB39CBDB7B@tuxera.com>
References: <20210217155930.1506815-1-rkovhaev@gmail.com>
In-Reply-To: <20210217155930.1506815-1-rkovhaev@gmail.com>
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Hi Andrew,

Can you please push this one upstream?  Thanks a lot in advance!

Best regards,

	Anton

> On 17 Feb 2021, at 15:59, Rustam Kovhaev <rkovhaev@gmail.com> wrote:
> 
> we should check for valid STANDARD_INFORMATION attribute offset and
> length before trying to access it
> 
> Reported-and-tested-by: syzbot+c584225dabdea2f71969@syzkaller.appspotmail.com
> Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
> Acked-by: Anton Altaparmakov <anton@tuxera.com>
> Link: https://syzkaller.appspot.com/bug?extid=c584225dabdea2f71969
> ---
> fs/ntfs/inode.c | 6 ++++++
> 1 file changed, 6 insertions(+)
> 
> diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
> index f7e4cbc26eaf..be4ff9386ec0 100644
> --- a/fs/ntfs/inode.c
> +++ b/fs/ntfs/inode.c
> @@ -629,6 +629,12 @@ static int ntfs_read_locked_inode(struct inode *vi)
> 	}
> 	a = ctx->attr;
> 	/* Get the standard information attribute value. */
> +	if ((u8 *)a + le16_to_cpu(a->data.resident.value_offset)
> +			+ le32_to_cpu(a->data.resident.value_length) >
> +			(u8 *)ctx->mrec + vol->mft_record_size) {
> +		ntfs_error(vi->i_sb, "Corrupt standard information attribute in inode.");
> +		goto unm_err_out;
> +	}
> 	si = (STANDARD_INFORMATION*)((u8*)a +
> 			le16_to_cpu(a->data.resident.value_offset));
> 
> -- 
> 2.30.0
> 


-- 
Anton Altaparmakov <anton at tuxera.com> (replace at with @)
Lead in File System Development, Tuxera Inc., http://www.tuxera.com/
Linux NTFS maintainer