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From: Huang Jianan <huangjianan@oppo.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Chengguang Xu <cgxu519@139.com>,
	overlayfs <linux-unionfs@vger.kernel.org>,
	linux-erofs@lists.ozlabs.org, xiang@kernel.org, chao@kernel.org,
	guoweichao@oppo.com, yh@oppo.com, zhangshiming@oppo.com,
	guanyuwei@oppo.com, jnhuang95@gmail.com,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Chengguang Xu <cgxu519@mykernel.net>
Subject: Re: [PATCH v3] ovl: fix null pointer when filesystemdoesn'tsupportdirect IO
Date: Tue, 28 Sep 2021 15:01:14 +0800	[thread overview]
Message-ID: <97977a2c-28d5-1324-fb1e-3e23ab4b1340@oppo.com> (raw)
In-Reply-To: <YVGRMoRTH4oJpxWZ@miu.piliscsaba.redhat.com>

在 2021/9/27 17:38, Miklos Szeredi 写道:
> On Wed, Sep 22, 2021 at 04:00:47PM +0200, Miklos Szeredi wrote:
>
>> First let's fix the oops: ovl_read_iter()/ovl_write_iter() must check
>> real file's ->direct_IO if IOCB_DIRECT is set in iocb->ki_flags and
>> return -EINVAL if not.
> And here's that fix.  Please test.

This patch can fix the oops.

Tested-by: Huang Jianan <huangjianan@oppo.com>

Thanks,
Jianan

> Thanks,
> Miklos
>
> ---
> From: Miklos Szeredi <mszeredi@redhat.com>
> Subject: ovl: fix IOCB_DIRECT if underlying fs doesn't support direct IO
>
> Normally the check at open time suffices, but e.g loop device does set
> IOCB_DIRECT after doing its own checks (which are not sufficent for
> overlayfs).
>
> Make sure we don't call the underlying filesystem read/write method with
> the IOCB_DIRECT if it's not supported.
>
> Reported-by: Huang Jianan <huangjianan@oppo.com>
> Fixes: 16914e6fc7e1 ("ovl: add ovl_read_iter()")
> Cc: <stable@vger.kernel.org> # v4.19
> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> ---
>   fs/overlayfs/file.c |   15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
>
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -296,6 +296,12 @@ static ssize_t ovl_read_iter(struct kioc
>   	if (ret)
>   		return ret;
>   
> +	ret = -EINVAL;
> +	if (iocb->ki_flags & IOCB_DIRECT &&
> +	    (!real.file->f_mapping->a_ops ||
> +	     !real.file->f_mapping->a_ops->direct_IO))
> +		goto out_fdput;
> +
>   	old_cred = ovl_override_creds(file_inode(file)->i_sb);
>   	if (is_sync_kiocb(iocb)) {
>   		ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
> @@ -320,7 +326,7 @@ static ssize_t ovl_read_iter(struct kioc
>   out:
>   	revert_creds(old_cred);
>   	ovl_file_accessed(file);
> -
> +out_fdput:
>   	fdput(real);
>   
>   	return ret;
> @@ -349,6 +355,12 @@ static ssize_t ovl_write_iter(struct kio
>   	if (ret)
>   		goto out_unlock;
>   
> +	ret = -EINVAL;
> +	if (iocb->ki_flags & IOCB_DIRECT &&
> +	    (!real.file->f_mapping->a_ops ||
> +	     !real.file->f_mapping->a_ops->direct_IO))
> +		goto out_fdput;
> +
>   	if (!ovl_should_sync(OVL_FS(inode->i_sb)))
>   		ifl &= ~(IOCB_DSYNC | IOCB_SYNC);
>   
> @@ -384,6 +396,7 @@ static ssize_t ovl_write_iter(struct kio
>   	}
>   out:
>   	revert_creds(old_cred);
> +out_fdput:
>   	fdput(real);
>   
>   out_unlock:


  reply	other threads:[~2021-09-28  7:01 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-18 12:13 [PATCH] ovl: fix null pointer when filesystem doesn't support direct IO Huang Jianan
2021-09-22  1:56 ` Chengguang Xu
2021-09-22  3:39   ` Huang Jianan
2021-09-22  3:47 ` [PATCH v2] " Huang Jianan
2021-09-22  5:09   ` Chengguang Xu
2021-09-22  7:18     ` Huang Jianan
2021-09-22  7:23       ` [PATCH v3] " Huang Jianan
2021-09-22  8:06         ` Chengguang Xu
2021-09-22  8:24           ` Huang Jianan
2021-09-22 13:20             ` [PATCH v3] ovl: fix null pointer when filesystemdoesn'tsupportdirect IO Chengguang Xu
2021-09-22 14:00               ` Miklos Szeredi
2021-09-27  9:38                 ` Miklos Szeredi
2021-09-28  7:01                   ` Huang Jianan [this message]
2021-09-28  7:17                     ` Miklos Szeredi

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