net/mlx4_en: Prevent potential integer overflow calculating Hz

[ Upstream commit 54d3416 ]

The "freq" variable is in terms of MHz and "max_val_cycles" is in terms
of Hz.  The fact that "max_val_cycles" is a u64 suggests that support
for high frequency is intended but the "freq_khz * 1000" would overflow
the u32 type if we went above 4GHz.  Use unsigned long long type for the
mutliplication to prevent that.

Fixes: 31c128b ("net/mlx4_en: Choose time-stamping shift value according to HW frequency")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/aDbFHe19juIJKjsb@stanley.mountain
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Dan Carpenter

drivers/net/ethernet/mellanox/mlx4/en_clock.c

@@ -249,7 +249,7 @@ static const struct ptp_clock_info mlx4_en_ptp_clock_info = {
 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 max_val_cycles = freq_khz * 1000ULL * MLX4_EN_WRAP_AROUND_SEC;
 	u64 max_val_cycles_rounded = 1ULL << fls64(max_val_cycles - 1);
 	/* calculate max possible multiplier in order to fit in 64bit */
 	u64 max_mul = div64_u64(ULLONG_MAX, max_val_cycles_rounded);