[PATCH rdma-next 1/5] RDMA/umem: Avoid undefined behavior of rounddown_pow_of_two

[Leon Romanovsky <leon@kernel.org>]

From: Aharon Landau <aharonl@nvidia.com>

rounddown_pow_of_two is undefined when the input is 0. Therefore we need
to avoid it in ib_umem_find_best_pgsz and return 0.
Otherwise, it could result in incorrect page size.

Fixes: 3361c29e9279 ("RDMA/umem: Use simpler logic for ib_umem_find_best_pgsz()")
Signed-off-by: Aharon Landau <aharonl@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/core/umem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 95be8cc75d2e..baaf1bf22941 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -137,7 +137,7 @@ unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
 	 */
 	if (mask)
 		pgsz_bitmap &= GENMASK(count_trailing_zeros(mask), 0);
-	return rounddown_pow_of_two(pgsz_bitmap);
+	return pgsz_bitmap ? rounddown_pow_of_two(pgsz_bitmap) : 0;
 }
 EXPORT_SYMBOL(ib_umem_find_best_pgsz);

--
2.29.2