* [PATCH v3] fs/ntfs3: validate BOOT sectors_per_clusters
@ 2022-05-02 17:53 Randy Dunlap
2022-05-03 5:52 ` Namjae Jeon
0 siblings, 1 reply; 2+ messages in thread
From: Randy Dunlap @ 2022-05-02 17:53 UTC (permalink / raw)
To: linux-fsdevel
Cc: Randy Dunlap, syzbot+1631f09646bc214d2e76, Konstantin Komarov,
ntfs3, Alexander Viro, Andrew Morton, Kari Argillander,
Namjae Jeon, Matthew Wilcox
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
Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: syzbot+1631f09646bc214d2e76@syzkaller.appspotmail.com
Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Cc: ntfs3@lists.linux.dev
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kari Argillander <kari.argillander@stargateuniverse.net>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
---
v2: use Willy's suggestions
v3: use Namjae's suggestions -- but now Konstantin can decide.
drop Willy's Rev-by: tag due to changes
fs/ntfs3/super.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- linux-next-20220428.orig/fs/ntfs3/super.c
+++ linux-next-20220428/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;
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v3] fs/ntfs3: validate BOOT sectors_per_clusters
2022-05-02 17:53 [PATCH v3] fs/ntfs3: validate BOOT sectors_per_clusters Randy Dunlap
@ 2022-05-03 5:52 ` Namjae Jeon
0 siblings, 0 replies; 2+ messages in thread
From: Namjae Jeon @ 2022-05-03 5:52 UTC (permalink / raw)
To: Randy Dunlap
Cc: linux-fsdevel, syzbot+1631f09646bc214d2e76, Konstantin Komarov,
ntfs3, Alexander Viro, Andrew Morton, Kari Argillander,
Matthew Wilcox
2022-05-03 2:53 GMT+09:00, Randy Dunlap <rdunlap@infradead.org>:
> 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
>
> Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
> Reported-by: syzbot+1631f09646bc214d2e76@syzkaller.appspotmail.com
> Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
> Cc: ntfs3@lists.linux.dev
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Kari Argillander <kari.argillander@stargateuniverse.net>
> Cc: Namjae Jeon <linkinjeon@kernel.org>
> Cc: Matthew Wilcox <willy@infradead.org>
Looks good to me:)
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Thanks.
> ---
> v2: use Willy's suggestions
> v3: use Namjae's suggestions -- but now Konstantin can decide.
> drop Willy's Rev-by: tag due to changes
>
> fs/ntfs3/super.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> --- linux-next-20220428.orig/fs/ntfs3/super.c
> +++ linux-next-20220428/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;
>
>
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-05-03 5:52 ` Namjae Jeon
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