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 19:30:12 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Wenqing Liu <wenqingliu0120@...il.com>,
        Chao Yu <chao@...nel.org>, Jaegeuk Kim <jaegeuk@...nel.org>
Subject: Re: [PATCH 5.10 052/390] f2fs: fix to do sanity check on summary info

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).

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;
 	}
 

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