From: Peilin Ye <redacted>
Date: Sun, 13 Sep 2020 04:06:05 -0400

tipc_group_add_to_tree() returns silently if `key` matches `nkey` of an
existing node, causing tipc_group_create_member() to leak memory. Let
tipc_group_add_to_tree() return an error in such a case, so that
tipc_group_create_member() can handle it properly.

Fixes: 75da2163dbb6 ("tipc: introduce communication groups")
Reported-and-tested-by: syzbot+f95d90c454864b3b5bc9@syzkaller.appspotmail.com
Cc: Hillf Danton <redacted>
Link: https://syzkaller.appspot.com/bug?id=048390604fe1b60df34150265479202f10e13aff
Signed-off-by: Peilin Ye <redacted>
---
Change in v2:
    - let tipc_group_add_to_tree() return a real error code instead of -1.
      (Suggested by David Miller [off-list ref])

Applied and queued up for -stable, thank you.