Re: [External] : [syzbot] [ocfs2?] BUG: unable to handle kernel paging request in ocfs2_unlock_and_free_folios

[Mark Tinguely]

> The reproducer uses FAULT_INJECTION to make memory allocation fail, which
> causes __filemap_get_folio() to fail, when initializing w_folios[i] in
> ocfs2_grab_folios_for_write(), it only returns an error code and the 
value
> of w_folios[i] is the error code, which causes 
ocfs2_unlock_and_free_folios()
> to recycle the invalid w_folios[i] when releasing folios.
>
> Reported-by: syzbot+c2ea94ae47cd7e3881ec@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=c2ea94ae47cd7e3881ec
> Signed-off-by: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx>
> ---
>  fs/ocfs2/aops.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index 40b6bce12951..89aadc6cdd87 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -1071,6 +1071,7 @@ static int ocfs2_grab_folios_for_write(struct 
address_space *mapping,
>  			if (IS_ERR(wc->w_folios[i])) {
>  				ret = PTR_ERR(wc->w_folios[i]);
>  				mlog_errno(ret);
> +				wc->w_folios[i] = NULL;
>  				goto out;
>  			}
>  		}
> --
> 2.43.0

sorry for the cut and paste reply. My email system rejected and bounced 
the original email.

ACKed-by: Mark Tinguely <mark.tinguely@xxxxxxxxxx>