Re: [dpdk-dev] [PATCH] common/mlx5: fix bogus assert

[Slava Ovsiienko <viacheslavo@mellanox.com>]

Hi, Stephen

Thank you for the fix.

The exposed API to set MAC addresses:
- mlx5_mac_addr_set (invoked by rte_mac_addr_set ())
- mlx5_set_mc_addr_list (invoked by rte_eth_dev_set_mc_addr_list())

Both routines call mlx5_internal_mac_addr_add(), it in its turn calls
mlx5_nl_mac_addr_add() (that is subject of the patch).

mlx5_nl_mac_addr_add is internal function, not exposed external API,
the wrong parameter means the critical internal bug, so assert looks to be relevant here.
I would not remove MLX5_ASSERT at all but fix just it. 
Adding the parameter check and return an error is nice.
What do you think?

With best regards, Slava

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Tuesday, March 31, 2020 9:03
> To: Matan Azrad <matan@mellanox.com>; Shahaf Shuler
> <shahafs@mellanox.com>; Slava Ovsiienko <viacheslavo@mellanox.com>
> Cc: dev@dpdk.org; Stephen Hemminger <stephen@networkplumber.org>;
> Alexander Kozyrev <akozyrev@mellanox.com>
> Subject: [PATCH] common/mlx5: fix bogus assert
> 
> The MLX5 device supports up to 256 MAC addresses.
> The code flushes all MAC devices.
> 
> If DPDK is compiled with MLX5_DEBUG this would an assert.
> PANIC in mlx5_nl_mac_addr_flush():
> line 775	assert "(size_t)(i) < sizeof(mac_own) * 8" failed
> 
> The root cause is that mac_own is a pointer and is being used as a bitmap
> array. The sizeof(mac_own) would therfore be 64 but the number of entries
> to be flushed would be 256.
> 
> There is a whole set of asserts in MLX5 netlink code with the same bug; that
> should just be changed into proper error checks.
> 
> Fixes: 8e46d4e18f09 ("common/mlx5: improve assert control")
> Cc: akozyrev@mellanox.com
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  drivers/common/mlx5/mlx5_nl.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/common/mlx5/mlx5_nl.c
> b/drivers/common/mlx5/mlx5_nl.c index 549e787b04bf..69f5efa50aa8 100644
> --- a/drivers/common/mlx5/mlx5_nl.c
> +++ b/drivers/common/mlx5/mlx5_nl.c
> @@ -671,7 +671,9 @@ mlx5_nl_mac_addr_add(int nlsk_fd, unsigned int
> iface_idx,
> 
>  	ret = mlx5_nl_mac_addr_modify(nlsk_fd, iface_idx, mac, 1);
>  	if (!ret) {
> -		MLX5_ASSERT((size_t)(index) < sizeof(mac_own) * CHAR_BIT);
> +		if (index >= MLX5_MAX_MAC_ADDRESSES)
> +			return -EINVAL;
> +
>  		BITFIELD_SET(mac_own, index);
>  	}
>  	if (ret == -EEXIST)
> @@ -700,7 +702,9 @@ int
>  mlx5_nl_mac_addr_remove(int nlsk_fd, unsigned int iface_idx, uint64_t
> *mac_own,
>  			struct rte_ether_addr *mac, uint32_t index)  {
> -	MLX5_ASSERT((size_t)(index) < sizeof(mac_own) * CHAR_BIT);
> +	if (index >= MLX5_MAX_MAC_ADDRESSES)
> +		return -EINVAL;
> +
>  	BITFIELD_RESET(mac_own, index);
>  	return mlx5_nl_mac_addr_modify(nlsk_fd, iface_idx, mac, 0);  } @@ -
> 769,10 +773,12 @@ mlx5_nl_mac_addr_flush(int nlsk_fd, unsigned int
> iface_idx,  {
>  	int i;
> 
> +	if (n <= 0 || n >= MLX5_MAX_MAC_ADDRESSES)
> +		return;
> +
>  	for (i = n - 1; i >= 0; --i) {
>  		struct rte_ether_addr *m = &mac_addrs[i];
> 
> -		MLX5_ASSERT((size_t)(i) < sizeof(mac_own) * CHAR_BIT);
>  		if (BITFIELD_ISSET(mac_own, i))
>  			mlx5_nl_mac_addr_remove(nlsk_fd, iface_idx,
> mac_own, m,
>  						i);
> --
> 2.20.1