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net: Fix an unsafe loop on the list

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commit 1dae9f1187189bc09ff6d25ca97ead711f7e26f9 upstream.

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: b8273570f8 ("genetlink: fix netns vs. netlink table locking (2)")
Cc: stable@vger.kernel.org
Signed-off-by: Anastasia Kovaleva <a.kovaleva@yadro.com>
Reviewed-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20241003104431.12391-1-a.kovaleva@yadro.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Anastasia Kovaleva 2024-10-03 13:44:31 +03:00 • committed by Greg Kroah-Hartman
parent 563e6892e2
commit 3be342e033
2 changed files with 4 additions and 1 deletions
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2
include/net/sock.h
View file

@ -902,6 +902,8 @@ static inline void sk_add_bind2_node(struct sock *sk, struct hlist_head *list)
hlist_for_each_entry(__sk, list, sk_bind_node)
#define sk_for_each_bound_bhash2(__sk, list) \
hlist_for_each_entry(__sk, list, sk_bind2_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

3
net/netlink/af_netlink.c
View file

@ -2143,8 +2143,9 @@ 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);
}