[SECURITY PATCH 038/117] zfs: Fix possible integer overflows

[Daniel Kiper]

From: Darren Kenny <darren.kenny@oracle.com>

In all cases the problem is that the value being acted upon by
a left-shift is a 32-bit number which is then being used in the
context of a 64-bit number.

To avoid overflow we ensure that the number being shifted is 64-bit
before the shift is done.

Fixes: CID 73684, CID 73695, CID 73764

Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
 grub-core/fs/zfs/zfs.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c
index ca82eb878..9ef2fd61a 100644
--- a/grub-core/fs/zfs/zfs.c
+++ b/grub-core/fs/zfs/zfs.c
@@ -567,7 +567,7 @@ find_bestub (uberblock_phys_t * ub_array,
       ubptr = (uberblock_phys_t *) ((grub_properly_aligned_t *) ub_array
                                    + ((i << ub_shift)
                                       / sizeof (grub_properly_aligned_t)));
-      err = uberblock_verify (ubptr, offset, 1 << ub_shift);
+      err = uberblock_verify (ubptr, offset, (grub_size_t) 1 << ub_shift);
       if (err)
        {
          grub_errno = GRUB_ERR_NONE;
@@ -1546,7 +1546,7 @@ read_device (grub_uint64_t offset, struct 
grub_zfs_device_desc *desc,
 
            high = grub_divmod64 ((offset >> desc->ashift) + c,
                                  desc->n_children, &devn);
-           csize = bsize << desc->ashift;
+           csize = (grub_size_t) bsize << desc->ashift;
            if (csize > len)
              csize = len;
 
@@ -1638,8 +1638,8 @@ read_device (grub_uint64_t offset, struct 
grub_zfs_device_desc *desc,
 
            while (len > 0)
              {
-               grub_size_t csize;
-               csize = ((s / (desc->n_children - desc->nparity))
+               grub_size_t csize = s;
+               csize = ((csize / (desc->n_children - desc->nparity))
                         << desc->ashift);
                if (csize > len)
                  csize = len;
-- 
2.11.0