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RDMA/umem: Avoid undefined behavior of rounddown_pow_of_two()

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[ Upstream commit b79f2dc5ffe17b03ec8c55f0d63f65e87bcac676 ]

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 not rejecting an invalid page size which eventually causes a
kernel oops due to the logical inconsistency.

Fixes: 3361c29e92 ("RDMA/umem: Use simpler logic for ib_umem_find_best_pgsz()")
Link: https://lore.kernel.org/r/20210113121703.559778-2-leon@kernel.org
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>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Aharon Landau 2021-01-13 14:16:59 +02:00 committed by Greg Kroah-Hartman
parent eb8ca93e49
commit 56c1362981
1 changed files with 1 additions and 1 deletions
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2
drivers/infiniband/core/umem.c
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@ -126,7 +126,7 @@ 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);