linux-kernel - Re: [PATCH] btrfs: add a sanity check for csum root before fill the data csum

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241025184424.GL31418@twin.jikos.cz>
Date: Fri, 25 Oct 2024 20:44:24 +0200
From: David Sterba <dsterba@...e.cz>
To: Edward Adam Davis <eadavis@...com>
Cc: syzbot+5d2b33d7835870519b5f@...kaller.appspotmail.com, clm@...com,
	dsterba@...e.com, josef@...icpanda.com, linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] btrfs: add a sanity check for csum root before fill the
 data csum

On Wed, Oct 23, 2024 at 07:04:40PM +0800, Edward Adam Davis wrote:
> Syzbot reported a null-ptr-deref in btrfs_lookup_csums_bitmap.
> The btrfs info contains IGNOREDATACSUMS, which prevents the csum root from
> being loaded.
> Before filling in the csum data, check the flag BTRFS_FS_STATE_NO_DATA_CSUMS
> to confirm that the csum root has been loaded.
> 
> Reported-and-tested-by: syzbot+5d2b33d7835870519b5f@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=5d2b33d7835870519b5f
> Signed-off-by: Edward Adam Davis <eadavis@...com>

Added to for-next, thanks.

> ---
>  fs/btrfs/scrub.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index 3a3427428074..1ba4d8ba902b 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -1602,7 +1602,8 @@ static int scrub_find_fill_first_stripe(struct btrfs_block_group *bg,
>  	}
>  
>  	/* Now fill the data csum. */
> -	if (bg->flags & BTRFS_BLOCK_GROUP_DATA) {
> +	if (!test_bit(BTRFS_FS_STATE_NO_DATA_CSUMS, &fs_info->fs_state) &&

I've updatd the coment as this is double negation that could be
confusing on a quick read.

> +	    bg->flags & BTRFS_BLOCK_GROUP_DATA) {
>  		int sector_nr;
>  		unsigned long csum_bitmap = 0;
>  
> -- 
> 2.43.0
>