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Subject: Re: [PATCH v2] f2fs: fix null page reference in redirty_blocks
To:     Daeho Jeong <daeho43@gmail.com>, linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com
Cc:     Daeho Jeong <daehojeong@google.com>
References: <20210105041630.1393157-1-daeho43@gmail.com>
From:   Colin Ian King <colin.king@canonical.com>
Message-ID: <57be566b-89e2-04a1-9a8e-51e902fee96c@canonical.com>
Date:   Tue, 5 Jan 2021 09:34:25 +0000
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On 05/01/2021 04:16, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@google.com>
> 
> Fixed null page reference when find_lock_page() fails in
> redirty_blocks().
> 
> Signed-off-by: Daeho Jeong <daehojeong@google.com>
> Reported-by: Colin Ian King <colin.king@canonical.com>
> Fixes: 5fdb322ff2c2 ("f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE")
> ---
> v2: changed error value and break the loop when error occurs
> ---
>  fs/f2fs/file.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 9e5275716be8..d27173c24391 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -4060,8 +4060,10 @@ static int redirty_blocks(struct inode *inode, pgoff_t page_idx, int len)
>  
>  	for (i = 0; i < page_len; i++, redirty_idx++) {
>  		page = find_lock_page(mapping, redirty_idx);
> -		if (!page)
> -			ret = -ENOENT;
> +		if (!page) {
> +			ret = -ENOMEM;
> +			break;
> +		}
>  		set_page_dirty(page);
>  		f2fs_put_page(page, 1);
>  		f2fs_put_page(page, 0);
> 
Thanks, looks good to me.

Reviewed-by: Colin Ian King <colin.king@canonical.com>