From: Eugenia Emantayev Date: Thu, 27 Oct 2016 13:27:16 +0000 (+0300) Subject: net/mlx4_en: Resolve dividing by zero in 32-bit system X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4850cf4581578216468b7b3c3d06cc5abb0a697d;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git net/mlx4_en: Resolve dividing by zero in 32-bit system 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: 31c128b66e5b ("net/mlx4_en: Choose time-stamping shift value according to HW frequency") Signed-off-by: Eugenia Emantayev Signed-off-by: Tariq Toukan Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/mellanox/mlx4/en_clock.c b/drivers/net/ethernet/mellanox/mlx4/en_clock.c index 08fc5fc56d43..a5fc46bbcbe2 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_clock.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_clock.c @@ -245,8 +245,11 @@ 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);