[Xen-devel] [PATCH 09/10] blktap: device_info validation fixes.

[Daniel Stodden <daniel.stodden@xxxxxxxxxx>]

- Logical block size <= 4k is too paranoid.
- Use ilog2 and add more comments.
---
 drivers/block/blktap/device.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/block/blktap/device.c b/drivers/block/blktap/device.c
index 0e8eb0a..2379643 100644
--- a/drivers/block/blktap/device.c
+++ b/drivers/block/blktap/device.c
@@ -315,12 +315,13 @@ blktap_device_validate_info(struct blktap *tap,
        unsigned int phys_mask;
        int sector_order;
 
-       sector_order = ffs(info->sector_size) - 1;
+       /* sector size is is 2^(n >= 9) */
+       sector_order = ilog2(info->sector_size);
        if (sector_order <  9 ||
-           sector_order > 12 ||
            info->sector_size != 1U<<sector_order)
                goto fail;
 
+       /* make sure capacity doesn't overflow */
        if (!info->capacity ||
            (info->capacity > ULLONG_MAX >> sector_order))
                goto fail;
-- 
1.7.0.4


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