[PATCH] dm: Cast an operand to sector_t to prevent potential uint32_t overflow in unstripe_ctr()

[Gax-c]

From: Zichen Xie <zichenxie0...@gmail.com>

This was found by a static analyzer.
There may be a potential integer overflow issue in
unstripe_ctr(). uc->unstripe_offset and uc->unstripe_width are
defined as "sector_t"(uint64_t), while uc->unstripe,
uc->chunk_size and uc->stripes are all defined as "uint32_t".
The result of the calculation will be limited to "uint32_t"
without correct casting.
So, we recommend adding an extra cast to prevent potential
integer overflow.

Fixes: 18a5bf270532 ("dm: add unstriped target")
Signed-off-by: Zichen Xie <zichenxie0...@gmail.com>
---
 drivers/md/dm-unstripe.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-unstripe.c b/drivers/md/dm-unstripe.c
index 48587c16c445..e8a9432057dc 100644
--- a/drivers/md/dm-unstripe.c
+++ b/drivers/md/dm-unstripe.c
@@ -85,8 +85,8 @@ static int unstripe_ctr(struct dm_target *ti, unsigned int 
argc, char **argv)
        }
        uc->physical_start = start;
 
-       uc->unstripe_offset = uc->unstripe * uc->chunk_size;
-       uc->unstripe_width = (uc->stripes - 1) * uc->chunk_size;
+       uc->unstripe_offset = (sector_t)uc->unstripe * uc->chunk_size;
+       uc->unstripe_width = (sector_t)(uc->stripes - 1) * uc->chunk_size;
        uc->chunk_shift = is_power_of_2(uc->chunk_size) ? fls(uc->chunk_size) - 
1 : 0;
 
        tmp_len = ti->len;
-- 
2.34.1