diff options
| author | John Fastabend <john.fastabend@gmail.com> | 2018-01-04 20:02:09 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-03-03 10:24:35 +0100 |
| commit | be2b86901a346d1fc2e496ce5823541ef3f82737 (patch) | |
| tree | a4d7b387e6e6975f1deecdf5a31e87161afe5b67 /kernel/bpf | |
| parent | 5ac98131312a0c16280e216e8ee6debceec11e0f (diff) | |
bpf: sockmap missing NULL psock check
[ Upstream commit 5731a879d03bdaa00265f8ebc32dfd0e65d25276 ]
Add psock NULL check to handle a racing sock event that can get the
sk_callback_lock before this case but after xchg happens causing the
refcnt to hit zero and sock user data (psock) to be null and queued
for garbage collection.
Also add a comment in the code because this is a bit subtle and
not obvious in my opinion.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/sockmap.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c index dbd7b322a86b..1890be7ea9cd 100644 --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -588,8 +588,15 @@ static void sock_map_free(struct bpf_map *map) write_lock_bh(&sock->sk_callback_lock); psock = smap_psock_sk(sock); - smap_list_remove(psock, &stab->sock_map[i]); - smap_release_sock(psock, sock); + /* This check handles a racing sock event that can get the + * sk_callback_lock before this case but after xchg happens + * causing the refcnt to hit zero and sock user data (psock) + * to be null and queued for garbage collection. + */ + if (likely(psock)) { + smap_list_remove(psock, &stab->sock_map[i]); + smap_release_sock(psock, sock); + } write_unlock_bh(&sock->sk_callback_lock); } rcu_read_unlock(); |