The kernel may crash when deleting a genetlink family if there are still
listeners for that family:
_______________________________________________________________________
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP [c000000000c080bc] netlink_update_socket_mc+0x3c/0xc0
LR [c000000000c0f764] __netlink_clear_multicast_users+0x74/0xc0
Call Trace:
__netlink_clear_multicast_users+0x74/0xc0
genl_unregister_family+0xd4/0x2d0
_______________________________________________________________________
Change the unsafe loop on the list to a safe one, because inside the
loop there is an element removal from this list.
Fixes: b8273570f802 ("genetlink: fix netns vs. netlink table locking (2)")
Signed-off-by: Anastasia Kovaleva <a.kovaleva@xxxxxxxxx>
Reviewed-by: Dmitry Bogdanov <d.bogdanov@xxxxxxxxx>
---
include/net/sock.h | 2 ++
net/netlink/af_netlink.c | 3 ++-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index c58ca8dd561b..eec77a18602a 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -894,6 +894,8 @@ static inline void sk_add_bind_node(struct sock *sk,
hlist_for_each_entry_safe(__sk, tmp, list, sk_node)
#define sk_for_each_bound(__sk, list) \
hlist_for_each_entry(__sk, list, sk_bind_node)
+#define sk_for_each_bound_safe(__sk, tmp, list) \
+ hlist_for_each_entry_safe(__sk, tmp, list, sk_bind_node)
/**
* sk_for_each_entry_offset_rcu - iterate over a list at a given struct offset
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 0b7a89db3ab7..0a9287fadb47 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2136,8 +2136,9 @@ void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
{
struct sock *sk;
struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
+ struct hlist_node *tmp;
- sk_for_each_bound(sk, &tbl->mc_list)
+ sk_for_each_bound_safe(sk, tmp, &tbl->mc_list)
netlink_update_socket_mc(nlk_sk(sk), group, 0);
}
--
2.40.1
