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| Started by | Mikulas Patocka <mpatocka@redhat.com> |
|---|---|
| First post | 2017-09-13 15:20 +0200 |
| Last post | 2017-09-13 19:20 +0200 |
| Articles | 3 — 3 participants |
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[PATCH] brd: fix overflow in __brd_direct_access Mikulas Patocka <mpatocka@redhat.com> - 2017-09-13 15:20 +0200
Re: [PATCH] brd: fix overflow in __brd_direct_access Dan Williams <dan.j.williams@intel.com> - 2017-09-13 18:30 +0200
Re: [PATCH] brd: fix overflow in __brd_direct_access Jens Axboe <axboe@kernel.dk> - 2017-09-13 19:20 +0200
| From | Mikulas Patocka <mpatocka@redhat.com> |
|---|---|
| Date | 2017-09-13 15:20 +0200 |
| Subject | [PATCH] brd: fix overflow in __brd_direct_access |
| Message-ID | <upfKa-7Rm-11@gated-at.bofh.it> |
The code in __brd_direct_access multiplies the pgoff variable by page size
and divides it by 512. It can cause overflow on 32-bit architectures. The
overflow happens if we create ramdisk larger than 4G and use it as a
sparse device.
This patch replaces multiplication and division with multiplication by the
number of sectors per page.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 1647b9b959c7 ("brd: add dax_operations support")
Cc: stable@vger.kernel.org # 4.12+
---
drivers/block/brd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-4.13/drivers/block/brd.c
===================================================================
--- linux-4.13.orig/drivers/block/brd.c
+++ linux-4.13/drivers/block/brd.c
@@ -339,7 +339,7 @@ static long __brd_direct_access(struct b
if (!brd)
return -ENODEV;
- page = brd_insert_page(brd, PFN_PHYS(pgoff) / 512);
+ page = brd_insert_page(brd, (sector_t)pgoff << PAGE_SECTORS_SHIFT);
if (!page)
return -ENOSPC;
*kaddr = page_address(page);
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| From | Dan Williams <dan.j.williams@intel.com> |
|---|---|
| Date | 2017-09-13 18:30 +0200 |
| Message-ID | <upiI1-1gS-9@gated-at.bofh.it> |
| In reply to | #1731602 |
On Wed, Sep 13, 2017 at 6:17 AM, Mikulas Patocka <mpatocka@redhat.com> wrote:
> The code in __brd_direct_access multiplies the pgoff variable by page size
> and divides it by 512. It can cause overflow on 32-bit architectures. The
> overflow happens if we create ramdisk larger than 4G and use it as a
> sparse device.
>
> This patch replaces multiplication and division with multiplication by the
> number of sectors per page.
>
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Fixes: 1647b9b959c7 ("brd: add dax_operations support")
> Cc: stable@vger.kernel.org # 4.12+
>
> ---
> drivers/block/brd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Index: linux-4.13/drivers/block/brd.c
> ===================================================================
> --- linux-4.13.orig/drivers/block/brd.c
> +++ linux-4.13/drivers/block/brd.c
> @@ -339,7 +339,7 @@ static long __brd_direct_access(struct b
>
> if (!brd)
> return -ENODEV;
> - page = brd_insert_page(brd, PFN_PHYS(pgoff) / 512);
> + page = brd_insert_page(brd, (sector_t)pgoff << PAGE_SECTORS_SHIFT);
Looks good to me, you can add:
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
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| From | Jens Axboe <axboe@kernel.dk> |
|---|---|
| Date | 2017-09-13 19:20 +0200 |
| Message-ID | <upjup-1Ow-3@gated-at.bofh.it> |
| In reply to | #1731602 |
On 09/13/2017 07:17 AM, Mikulas Patocka wrote: > The code in __brd_direct_access multiplies the pgoff variable by page size > and divides it by 512. It can cause overflow on 32-bit architectures. The > overflow happens if we create ramdisk larger than 4G and use it as a > sparse device. > > This patch replaces multiplication and division with multiplication by the > number of sectors per page. Thanks, applied with Dan's ack. -- Jens Axboe
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