diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2018-08-16 21:49:09 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2018-08-16 14:58:08 -0700 |
| commit | 166ab6f0a0702fdd4d865ad5090bf3094ed83428 (patch) | |
| tree | 16e5a7b40f898efe4a8976cb2e179ec2f1b7ce3b /kernel | |
| parent | d40b0116c94bd8fc2b63aae35ce8e66bb53bba42 (diff) | |
bpf, sockmap: fix map elem deletion race with smap_stop_sock
The smap_start_sock() and smap_stop_sock() are each protected under
the sock->sk_callback_lock from their call-sites except in the case
of sock_map_delete_elem() where we drop the old socket from the map
slot. This is racy because the same sock could be part of multiple
sock maps, so we run smap_stop_sock() in parallel, and given at that
point psock->strp_enabled might be true on both CPUs, we might for
example wrongly restore the sk->sk_data_ready / sk->sk_write_space.
Therefore, hold the sock->sk_callback_lock as well on delete. Looks
like 2f857d04601a ("bpf: sockmap, remove STRPARSER map_flags and add
multi-map support") had this right, but later on e9db4ef6bf4c ("bpf:
sockhash fix omitted bucket lock in sock_close") removed it again
from delete leaving this smap_stop_sock() instance unprotected.
Fixes: e9db4ef6bf4c ("bpf: sockhash fix omitted bucket lock in sock_close")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/sockmap.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c index 94a324bc6afc..921cb6b8c862 100644 --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -1786,8 +1786,11 @@ static int sock_map_delete_elem(struct bpf_map *map, void *key) if (!psock) goto out; - if (psock->bpf_parse) + if (psock->bpf_parse) { + write_lock_bh(&sock->sk_callback_lock); smap_stop_sock(psock, sock); + write_unlock_bh(&sock->sk_callback_lock); + } smap_list_map_remove(psock, &stab->sock_map[k]); smap_release_sock(psock, sock); out: |