[Linux-kernel-mentees] [PATCH net v2] tipc: Fix memory leak in tipc_group_create_member()

Peilin Ye
2020-09-13T08:07:18Z

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 <hdanton@sina.com>
Link: https://syzkaller.appspot.com/bug?id=048390604fe1b60df34150265479202f10e13aff
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
---
Change in v2:
- let tipc_group_add_to_tree() return a real error code instead of -1.
(Suggested by David Miller <davem@davemloft.net>)

net/tipc/group.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/net/tipc/group.c b/net/tipc/group.c
index 588c2d2b0c69..b1fcd2ad5ecf 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -273,8 +273,8 @@ static struct tipc_member *tipc_group_find_node(struct tipc_group *grp,
return NULL;
}

-static void tipc_group_add_to_tree(struct tipc_group *grp,
- struct tipc_member *m)
+static int tipc_group_add_to_tree(struct tipc_group *grp,
+ struct tipc_member *m)
{
u64 nkey, key = (u64)m->node << 32 | m->port;
struct rb_node **n, *parent = NULL;
@@ -291,10 +291,11 @@ static void tipc_group_add_to_tree(struct tipc_group *grp,
else if (key > nkey)
n = &(*n)->rb_right;
else
- return;
+ return -EEXIST;
}
rb_link_node(&m->tree_node, parent, n);
rb_insert_color(&m->tree_node, &grp->members);
+ return 0;
}

static struct tipc_member *tipc_group_create_member(struct tipc_group *grp,
@@ -302,6 +303,7 @@ static struct tipc_member *tipc_group_create_member(struct tipc_group *grp,
u32 instance, int state)
{
struct tipc_member *m;
+ int ret;

m = kzalloc(sizeof(*m), GFP_ATOMIC);
if (!m)
@@ -314,8 +316,12 @@ static struct tipc_member *tipc_group_create_member(struct tipc_group *grp,
m->port = port;
m->instance = instance;
m->bc_acked = grp->bc_snd_nxt - 1;
+ ret = tipc_group_add_to_tree(grp, m);
+ if (ret < 0) {
+ kfree(m);
+ return NULL;
+ }
grp->member_cnt++;
- tipc_group_add_to_tree(grp, m);
tipc_nlist_add(&grp->dests, m->node);
m->state = state;
return m;
--
2.25.1