On some kernels the string attributes within Netlink
reply messages might be not padded with zeroes (in cases
when string length is aligned with 4-byte boundary).
This caused wrong physical port names recognition and
mlx5 PMD load failures.

Fixes: 30a86157f6d5 ("net/mlx5: support PF representor")
Cc: sta...@dpdk.org

Signed-off-by: Viacheslav Ovsiienko <viachesl...@nvidia.com>
---
 drivers/common/mlx5/linux/mlx5_nl.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/common/mlx5/linux/mlx5_nl.c 
b/drivers/common/mlx5/linux/mlx5_nl.c
index f0d04f9473..3f1912d078 100644
--- a/drivers/common/mlx5/linux/mlx5_nl.c
+++ b/drivers/common/mlx5/linux/mlx5_nl.c
@@ -33,6 +33,8 @@
 #define MLX5_SEND_BUF_SIZE 32768
 /* Receive buffer size for the Netlink socket */
 #define MLX5_RECV_BUF_SIZE 32768
+/* Maximal physical port name length. */
+#define MLX5_PHYS_PORT_NAME_MAX 128
 
 /** Parameters of VLAN devices created by driver. */
 #define MLX5_VMWA_VLAN_DEVICE_PFX "evmlx"
@@ -1191,6 +1193,7 @@ mlx5_nl_switch_info_cb(struct nlmsghdr *nh, void *arg)
        size_t off = NLMSG_LENGTH(sizeof(struct ifinfomsg));
        bool switch_id_set = false;
        bool num_vf_set = false;
+       int len;
 
        if (nh->nlmsg_type != RTM_NEWLINK)
                goto error;
@@ -1206,7 +1209,24 @@ mlx5_nl_switch_info_cb(struct nlmsghdr *nh, void *arg)
                        num_vf_set = true;
                        break;
                case IFLA_PHYS_PORT_NAME:
-                       mlx5_translate_port_name((char *)payload, &info);
+                       len = RTA_PAYLOAD(ra);
+                       /* Some kernels do not pad attributes with zero. */
+                       if (len > 0 && len < MLX5_PHYS_PORT_NAME_MAX) {
+                               char name[MLX5_PHYS_PORT_NAME_MAX];
+
+                               /*
+                                * We can't just patch the message with padding
+                                * zero - it might corrupt the following items
+                                * in the message, we have to copy the string
+                                * by attribute length and pad the copied one.
+                                */
+                               memcpy(name, payload, len);
+                               name[len] = 0;
+                               mlx5_translate_port_name(name, &info);
+                       } else {
+                               info.name_type =
+                                       MLX5_PHYS_PORT_NAME_TYPE_UNKNOWN;
+                       }
                        break;
                case IFLA_PHYS_SWITCH_ID:
                        info.switch_id = 0;
-- 
2.18.1

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