The patch titled
Subject: fs/ntfs3: validate BOOT sectors_per_clusters
has been added to the -mm mm-nonmm-unstable branch. Its filename is
fs-ntfs3-validate-boot-sectors_per_clusters.patch
This patch should soon appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Subject: fs/ntfs3: validate BOOT sectors_per_clusters
When the NTFS BOOT sectors_per_clusters field is > 0x80, it represents a
shift value. Make sure that the shift value is not too large before using
it (NTFS max cluster size is 2MB). Return -EVINVAL if it too large.
This prevents negative shift values and shift values that are larger than
the field size.
Prevents this UBSAN error:
UBSAN: shift-out-of-bounds in ../fs/ntfs3/super.c:673:16
shift exponent -192 is negative
Link: https://lkml.kernel.org/r/20220502175342.20296-1-rdunlap@xxxxxxxxxxxxx
Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Reported-by: syzbot+1631f09646bc214d2e76@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Cc: Konstantin Komarov <almaz.alexandrovich@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Kari Argillander <kari.argillander@xxxxxxxxxxxxxxxxxxxx>
Cc: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ntfs3/super.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/fs/ntfs3/super.c~fs-ntfs3-validate-boot-sectors_per_clusters
+++ a/fs/ntfs3/super.c
@@ -668,9 +668,11 @@ static u32 format_size_gb(const u64 byte
static u32 true_sectors_per_clst(const struct NTFS_BOOT *boot)
{
- return boot->sectors_per_clusters <= 0x80
- ? boot->sectors_per_clusters
- : (1u << (0 - boot->sectors_per_clusters));
+ if (boot->sectors_per_clusters <= 0x80)
+ return boot->sectors_per_clusters;
+ if (boot->sectors_per_clusters >= 0xf4) /* limit shift to 2MB max */
+ return 1U << (0 - boot->sectors_per_clusters);
+ return -EINVAL;
}
/*
@@ -713,6 +715,8 @@ static int ntfs_init_from_boot(struct su
/* cluster size: 512, 1K, 2K, 4K, ... 2M */
sct_per_clst = true_sectors_per_clst(boot);
+ if ((int)sct_per_clst < 0)
+ goto out;
if (!is_power_of_2(sct_per_clst))
goto out;
_
Patches currently in -mm which might be from rdunlap@xxxxxxxxxxxxx are
fs-ntfs3-validate-boot-sectors_per_clusters.patch
