[PATCH v3 0/1] ufs: ufs_sb_private_info: remove unused s_{2,3}apb fields

[PATCH v3 0/1] ufs: ufs_sb_private_info: remove unused s_{2,3}apb fields

[Agathe Porte]

v3: drop stable Cc as requested (because the value is not used), and
    reformulate patch description

Agathe Porte (1):
  ufs: ufs_sb_private_info: remove unused s_{2,3}apb fields

 fs/ufs/super.c  | 4 ----
 fs/ufs/ufs_fs.h | 4 ----
 2 files changed, 8 deletions(-)

-- 
2.43.0

[PATCH v3 1/1] ufs: ufs_sb_private_info: remove unused s_{2,3}apb fields

[Agathe Porte]

These two fields are populated 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@canonical.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 */
-- 
2.43.0

Re: [PATCH v3 1/1] ufs: ufs_sb_private_info: remove unused s_{2,3}apb fields

[Al Viro]

On Tue, Nov 12, 2024 at 01:18:25PM +0100, Agathe Porte wrote:
> These two fields are populated 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@canonical.com>

Applied to viro/vfs.git#work.ufs