linux-kernel - Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx

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Message-ID: <k6wt52qxkvfubt73ty7ix4s7gnxlh7336zsfkvz2umopuqofhu@j3grduxsmtxj>
Date: Thu, 24 Oct 2024 07:30:55 -0400
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: Jeongjun Park <aha310510@...il.com>
Cc: mmpgouride@...il.com, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzbot+7f45fa9805c40db3f108@...kaller.appspotmail.com
Subject: Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

On Tue, Oct 22, 2024 at 12:43:56AM +0900, Jeongjun Park wrote:
> The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
> To fix this, we need to add validation on a.data_type in 
> alloc_lru_idx_fragmentation().
> 
> Reported-by: syzbot+7f45fa9805c40db3f108@...kaller.appspotmail.com
> Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
> Signed-off-by: Jeongjun Park <aha310510@...il.com>

Thanks, applied

> ---
>  fs/bcachefs/alloc_background.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
> index f8e87c6721b1..163a67b97a40 100644
> --- a/fs/bcachefs/alloc_background.h
> +++ b/fs/bcachefs/alloc_background.h
> @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
>  static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
>  					      struct bch_dev *ca)
>  {
> +	if (a.data_type >= BCH_DATA_NR)
> +		return 0;
> +
>  	if (!data_type_movable(a.data_type) ||
>  	    !bch2_bucket_sectors_fragmented(ca, a))
>  		return 0;
> --