[PATCH iproute2-next] rdma: Check comm string before print in print_comm()

[Leon Romanovsky]

From: Mark Zhang <ma...@mellanox.com>

Broken kernels (not-upstream) can provide wrong empty "comm" field.
It causes to segfault while printing in JSON format.

Fixes: 8ecac46a60ff ("rdma: Add QP resource tracking information")
Signed-off-by: Mark Zhang <ma...@mellanox.com>
Signed-off-by: Leon Romanovsky <leo...@mellanox.com>
---
 rdma/res.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/rdma/res.c b/rdma/res.c
index 97a7b964..6003006e 100644
--- a/rdma/res.c
+++ b/rdma/res.c
@@ -161,6 +161,9 @@ void print_comm(struct rd *rd, const char *str, struct 
nlattr **nla_line)
 {
        char tmp[18];
 
+       if (!str)
+               return;
+
        if (rd->json_output) {
                /* Don't beatify output in JSON format */
                jsonw_string_field(rd->jw, "comm", str);
-- 
2.20.1