linux-kernel - Re: [PATCH] f2fs: fix to do sanity check for inline inode

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Date:   Fri, 13 May 2022 14:07:37 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Ming Yan <yanming@....edu.cn>, Chao Yu <chao.yu@...o.com>
Subject: Re: [PATCH] f2fs: fix to do sanity check for inline inode

On 04/28, Chao Yu wrote:
> As Yanming reported in bugzilla:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=215895
> 
> I have encountered a bug in F2FS file system in kernel v5.17.
> 
> The kernel message is shown below:
> 
> kernel BUG at fs/inode.c:611!
> Call Trace:
>  evict+0x282/0x4e0
>  __dentry_kill+0x2b2/0x4d0
>  dput+0x2dd/0x720
>  do_renameat2+0x596/0x970
>  __x64_sys_rename+0x78/0x90
>  do_syscall_64+0x3b/0x90
> 
> The root cause is: fuzzed inode has both inline_data flag and encrypted
> flag, so after it was deleted by rename(), during f2fs_evict_inode(),
> it will cause inline data conversion due to flags confilction, then
> page cache will be polluted and trigger panic in clear_inode().
> 
> This patch tries to fix the issue by do more sanity checks for inline
> data inode in sanity_check_inode().
> 
> Cc: stable@...r.kernel.org
> Reported-by: Ming Yan <yanming@....edu.cn>
> Signed-off-by: Chao Yu <chao.yu@...o.com>
> ---
>  fs/f2fs/f2fs.h  | 7 +++++++
>  fs/f2fs/inode.c | 3 +--
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 27aa93caec06..64c511b498cc 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4173,6 +4173,13 @@ static inline void f2fs_set_encrypted_inode(struct inode *inode)
>   */
>  static inline bool f2fs_post_read_required(struct inode *inode)
>  {
> +	/*
> +	 * used by sanity_check_inode(), when disk layout fields has not
> +	 * been synchronized to inmem fields.
> +	 */
> +	if (file_is_encrypt(inode) || file_is_verity(inode) ||
> +			F2FS_I(inode)->i_flags & F2FS_COMPR_FL)
> +		return true;
>  	return f2fs_encrypted_file(inode) || fsverity_active(inode) ||
>  		f2fs_compressed_file(inode);
>  }
> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> index 83639238a1fe..234b8ed02644 100644
> --- a/fs/f2fs/inode.c
> +++ b/fs/f2fs/inode.c
> @@ -276,8 +276,7 @@ static bool sanity_check_inode(struct inode *inode, struct page *node_page)
>  		}
>  	}
>  
> -	if (f2fs_has_inline_data(inode) &&
> -			(!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode))) {
> +	if (f2fs_has_inline_data(inode) && !f2fs_may_inline_data(inode)) {

BTW, why can't we just check the above on-disk fields here only?

>  		set_sbi_flag(sbi, SBI_NEED_FSCK);
>  		f2fs_warn(sbi, "%s: inode (ino=%lx, mode=%u) should not have inline_data, run fsck to fix",
>  			  __func__, inode->i_ino, inode->i_mode);
> -- 
> 2.25.1