diff options
| author | Xin Long <lucien.xin@gmail.com> | 2017-09-06 11:47:12 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-09-06 21:22:53 -0700 |
| commit | be82485fbcbb1cf11b13e7356231c72fdf21241c (patch) | |
| tree | cecff3d0ec55ca784f503188ab4b4d4fbef37466 /net/netlink/af_netlink.c | |
| parent | 39ad1297a2084e0724da73d9eda2ceb9573a5d6c (diff) | |
| download | lwn-be82485fbcbb1cf11b13e7356231c72fdf21241c.tar.gz lwn-be82485fbcbb1cf11b13e7356231c72fdf21241c.zip | |
netlink: fix an use-after-free issue for nlk groups
ChunYu found a netlink use-after-free issue by syzkaller:
[28448.842981] BUG: KASAN: use-after-free in __nla_put+0x37/0x40 at addr ffff8807185e2378
[28448.969918] Call Trace:
[...]
[28449.117207] __nla_put+0x37/0x40
[28449.132027] nla_put+0xf5/0x130
[28449.146261] sk_diag_fill.isra.4.constprop.5+0x5a0/0x750 [netlink_diag]
[28449.176608] __netlink_diag_dump+0x25a/0x700 [netlink_diag]
[28449.202215] netlink_diag_dump+0x176/0x240 [netlink_diag]
[28449.226834] netlink_dump+0x488/0xbb0
[28449.298014] __netlink_dump_start+0x4e8/0x760
[28449.317924] netlink_diag_handler_dump+0x261/0x340 [netlink_diag]
[28449.413414] sock_diag_rcv_msg+0x207/0x390
[28449.432409] netlink_rcv_skb+0x149/0x380
[28449.467647] sock_diag_rcv+0x2d/0x40
[28449.484362] netlink_unicast+0x562/0x7b0
[28449.564790] netlink_sendmsg+0xaa8/0xe60
[28449.661510] sock_sendmsg+0xcf/0x110
[28449.865631] __sys_sendmsg+0xf3/0x240
[28450.000964] SyS_sendmsg+0x32/0x50
[28450.016969] do_syscall_64+0x25c/0x6c0
[28450.154439] entry_SYSCALL64_slow_path+0x25/0x25
It was caused by no protection between nlk groups' free in netlink_release
and nlk groups' accessing in sk_diag_dump_groups. The similar issue also
exists in netlink_seq_show().
This patch is to defer nlk groups' free in deferred_put_nlk_sk.
Reported-by: ChunYu Wang <chunwang@redhat.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netlink/af_netlink.c')
| -rw-r--r-- | net/netlink/af_netlink.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 5acee49db90b..94a61e602ee7 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -691,6 +691,9 @@ static void deferred_put_nlk_sk(struct rcu_head *head) struct netlink_sock *nlk = container_of(head, struct netlink_sock, rcu); struct sock *sk = &nlk->sk; + kfree(nlk->groups); + nlk->groups = NULL; + if (!refcount_dec_and_test(&sk->sk_refcnt)) return; @@ -769,9 +772,6 @@ static int netlink_release(struct socket *sock) netlink_table_ungrab(); } - kfree(nlk->groups); - nlk->groups = NULL; - local_bh_disable(); sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1); local_bh_enable(); |