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RDMA/umem: Avoid undefined behavior of rounddown_pow_of_two() 

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>
This commit is contained in:
Aharon Landau 2021-01-13 14:16:59 +02:00 committed by Jason Gunthorpe
parent f2bc3af635
commit b79f2dc5ff
1 changed files with 1 additions and 1 deletions
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2
drivers/infiniband/core/umem.c
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@ -135,7 +135,7 @@ unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
*/ */
if (mask) if (mask)
pgsz_bitmap &= GENMASK(count_trailing_zeros(mask), 0); 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); EXPORT_SYMBOL(ib_umem_find_best_pgsz);