linux-kernel - Re: [PATCH 5.10 052/390] f2fs: fix to do sanity check on summary info

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Date:   Mon, 24 Oct 2022 11:08:20 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Pavel Machek <pavel@...x.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Wenqing Liu <wenqingliu0120@...il.com>,
        Chao Yu <chao@...nel.org>
Subject: Re: [PATCH 5.10 052/390] f2fs: fix to do sanity check on summary info

On 10/24, Pavel Machek wrote:
> Hi!
> 
> > From: Chao Yu <chao@...nel.org>
> > 
> > commit c6ad7fd16657ebd34a87a97d9588195aae87597d upstream.
> > 
> > As Wenqing Liu reported in bugzilla:
> > 
> > https://bugzilla.kernel.org/show_bug.cgi?id=216456
> > 
> > BUG: KASAN: use-after-free in recover_data+0x63ae/0x6ae0 [f2fs]
> > Read of size 4 at addr ffff8881464dcd80 by task mount/1013
> 
> I believe this is missing put_page on the error path:
> 
> > +++ b/fs/f2fs/gc.c
> > @@ -1003,6 +1003,14 @@ static bool is_alive(struct f2fs_sb_info
> >  		return false;
> >  	}
> >  
> > +	max_addrs = IS_INODE(node_page) ? DEF_ADDRS_PER_INODE :
> > +						DEF_ADDRS_PER_BLOCK;
> > +	if (ofs_in_node >= max_addrs) {
> > +		f2fs_err(sbi, "Inconsistent ofs_in_node:%u in summary, ino:%u, nid:%u, max:%u",
> > +			ofs_in_node, dni->ino, dni->nid, max_addrs);
> > +		return false;
> > +	}
> > +
> >  	*nofs = ofs_of_node(node_page);
> >  	source_blkaddr = data_blkaddr(NULL, node_page, ofs_in_node);
> >  	f2fs_put_page(node_page, 1);
> 
> So something like this is needed. (Feel free to test/adapt/apply).

Urg.. thank you so much for pointing this out. Applied the change to the tree.

https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=a22aeafb3d3569aecf811dca1aceff656695cdb4

> 
> Signed-off-by: Pavel Machek <pavel@...x.de>
> 
> Best regards,
> 								Pavel
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 4546e01b2ee0..dab794225cce 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -1110,6 +1110,7 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>  	if (ofs_in_node >= max_addrs) {
>  		f2fs_err(sbi, "Inconsistent ofs_in_node:%u in summary, ino:%u, nid:%u, max:%u",
>  			ofs_in_node, dni->ino, dni->nid, max_addrs);
> +		f2fs_put_page(node_page, 1);
>  		return false;
>  	}
>  
> 
> -- 
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany