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authorDaniel Borkmann <daniel@iogearbox.net>2018-08-16 21:49:09 +0200
committerAlexei Starovoitov <ast@kernel.org>2018-08-16 14:58:08 -0700
commit166ab6f0a0702fdd4d865ad5090bf3094ed83428 (patch)
tree16e5a7b40f898efe4a8976cb2e179ec2f1b7ce3b /kernel/bpf
parentd40b0116c94bd8fc2b63aae35ce8e66bb53bba42 (diff)
downloadlinux-166ab6f0a0702fdd4d865ad5090bf3094ed83428.tar.bz2
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/bpf')
-rw-r--r--kernel/bpf/sockmap.c5
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: