Re: [PATCH 1/3] ext4: fix lost error code reporting in __ext4_fill_super()

[Jason Yan <yanaijie@huawei.com>]

On 2023/4/28 11:16, Theodore Ts'o wrote:
> When code was factored out of __ext4_fill_super() into
> ext4_percpu_param_init() the error return was discard.  This meant
> that it was possible for __ext4_fill_super() to return zero,
> indicating success, without the struct super getting completely filled
> in, leading to a potential NULL pointer dereference.
> 
> Reported-by: syzbot+bbf0f9a213c94f283a5c@syzkaller.appspotmail.com
> Fixes: 1f79467c8a6b ("ext4: factor out ext4_percpu_param_init() ...")
> Cc: Jason Yan <yanaijie@huawei.com>
> Link: https://syzkaller.appspot.com/bug?id=6dac47d5e58af770c0055f680369586ec32e144c
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---
>   fs/ext4/super.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 403cc0e6cd65..b11907e1fab2 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -5503,7 +5503,8 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
>   		sbi->s_journal->j_commit_callback =
>   			ext4_journal_commit_callback;
>   
> -	if (ext4_percpu_param_init(sbi))
> +	err = ext4_percpu_param_init(sbi);
> +	if (err)
>   		goto failed_mount6;
>   
>   	if (ext4_has_feature_flex_bg(sb))
> 

Reviewed-by: Jason Yan <yanaijie@huawei.com>