Patch "brd: fix overflow in __brd_direct_access" has been added to the 4.13-stable tree

Patch "brd: fix overflow in __brd_direct_access" has been added to the 4.13-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    brd: fix overflow in __brd_direct_access

to the 4.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     brd-fix-overflow-in-__brd_direct_access.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 02a4843618fb35f847cf8c31cd3893873aa0edde Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Wed, 13 Sep 2017 09:17:57 -0400
Subject: brd: fix overflow in __brd_direct_access

From: Mikulas Patocka <mpatocka@redhat.com>

commit 02a4843618fb35f847cf8c31cd3893873aa0edde upstream.

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.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 1647b9b959c7 ("brd: add dax_operations support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/block/brd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/block/brd.c
+++ b/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);


Patches currently in stable-queue which might be from mpatocka@redhat.com are

queue-4.13/brd-fix-overflow-in-__brd_direct_access.patch
queue-4.13/dax-remove-the-pmem_dax_ops-flush-abstraction.patch
queue-4.13/dm-integrity-do-not-check-integrity-for-failed-read-operations.patch