Commit 61918dbc authored by Eugenia Emantayev's avatar Eugenia Emantayev Committed by Greg Kroah-Hartman

net/mlx4_en: Resolve dividing by zero in 32-bit system

[ Upstream commit 4850cf45 ]

When doing roundup_pow_of_two for large enough number with
bit 31, an overflow will occur and a value equal to 1 will
be returned. In this case 1 will be subtracted from the return
value and division by zero will be reached.

Fixes: 31c128b6 ("net/mlx4_en: Choose time-stamping shift value according to HW frequency")
Signed-off-by: default avatarEugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: default avatarTariq Toukan <tariqt@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 80176161
......@@ -251,8 +251,11 @@ static u32 freq_to_shift(u16 freq)
{
u32 freq_khz = freq * 1000;
u64 max_val_cycles = freq_khz * 1000 * MLX4_EN_WRAP_AROUND_SEC;
u64 tmp_rounded =
roundup_pow_of_two(max_val_cycles) > max_val_cycles ?
roundup_pow_of_two(max_val_cycles) - 1 : UINT_MAX;
u64 max_val_cycles_rounded = is_power_of_2(max_val_cycles + 1) ?
max_val_cycles : roundup_pow_of_two(max_val_cycles) - 1;
max_val_cycles : tmp_rounded;
/* calculate max possible multiplier in order to fit in 64bit */
u64 max_mul = div_u64(0xffffffffffffffffULL, max_val_cycles_rounded);
......
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