linux-kernel - Re: [PATCH] ufs: ufs_sb_private_info: remove unused s

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Message-ID: <f23ce482-89d3-4198-8129-d0187fb04658@canonical.com>
Date: Tue, 12 Nov 2024 13:31:44 +0100
From: Agathe Porte <agathe.porte@...onical.com>
To: linux-kernel@...r.kernel.org
Cc: Jeff Johnson <quic_jjohnson@...cinc.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] ufs: ufs_sb_private_info: remove unused s_{2,3}apb fields

Replaced by v2 
https://lore.kernel.org/linux-kernel/20241112120304.32452-1-agathe.porte@canonical.com/T/#t 


Which was replaced by v3: 
https://lore.kernel.org/linux-kernel/20241112122000.35610-1-agathe.porte@canonical.com/T/#t

On 12/11/2024 12:44, Agathe Porte wrote:
> These two fields are populated during and stored as a "frequently used
> value" in ufs_fill_super, but are not used afterwards in the driver.
>
> Moreover, one of the shifts triggers UBSAN: shift-out-of-bounds when
> apbshift is 12 because 12 * 3 = 36 and 1 << 36 does not fit in the 32
> bit integer used to store the value.
>
> Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2087853
> Signed-off-by: Agathe Porte <agathe.porte@...onical.com>
> ---
>   fs/ufs/super.c  | 4 ----
>   fs/ufs/ufs_fs.h | 4 ----
>   2 files changed, 8 deletions(-)
>
> diff --git a/fs/ufs/super.c b/fs/ufs/super.c
> index bc625788589c..7ea1a4c07ba2 100644
> --- a/fs/ufs/super.c
> +++ b/fs/ufs/super.c
> @@ -1240,11 +1240,7 @@ static int ufs_fill_super(struct super_block *sb, void *data, int silent)
>   	else
>   		uspi->s_apbshift = uspi->s_bshift - 2;
>   
> -	uspi->s_2apbshift = uspi->s_apbshift * 2;
> -	uspi->s_3apbshift = uspi->s_apbshift * 3;
>   	uspi->s_apb = 1 << uspi->s_apbshift;
> -	uspi->s_2apb = 1 << uspi->s_2apbshift;
> -	uspi->s_3apb = 1 << uspi->s_3apbshift;
>   	uspi->s_apbmask = uspi->s_apb - 1;
>   	uspi->s_nspfshift = uspi->s_fshift - UFS_SECTOR_BITS;
>   	uspi->s_nspb = uspi->s_nspf << uspi->s_fpbshift;
> diff --git a/fs/ufs/ufs_fs.h b/fs/ufs/ufs_fs.h
> index ef9ead44776a..0905f9a16b91 100644
> --- a/fs/ufs/ufs_fs.h
> +++ b/fs/ufs/ufs_fs.h
> @@ -775,12 +775,8 @@ struct ufs_sb_private_info {
>   
>   	__u32	s_fpbmask;	/* fragments per block mask */
>   	__u32	s_apb;		/* address per block */
> -	__u32	s_2apb;		/* address per block^2 */
> -	__u32	s_3apb;		/* address per block^3 */
>   	__u32	s_apbmask;	/* address per block mask */
>   	__u32	s_apbshift;	/* address per block shift */
> -	__u32	s_2apbshift;	/* address per block shift * 2 */
> -	__u32	s_3apbshift;	/* address per block shift * 3 */
>   	__u32	s_nspfshift;	/* number of sector per fragment shift */
>   	__u32	s_nspb;		/* number of sector per block */
>   	__u32	s_inopf;	/* inodes per fragment */