6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michal Luczaj mhal@rbox.co
[ Upstream commit b3af60928ab9129befa65e6df0310d27300942bf ]
As pointed out in the original comment, lookup in sockmap can return a TCP ESTABLISHED socket. Such TCP socket may have had SO_ATTACH_REUSEPORT_EBPF set before it was ESTABLISHED. In other words, a non-NULL sk_reuseport_cb does not imply a non-refcounted socket.
Drop sk's reference in both error paths.
unreferenced object 0xffff888101911800 (size 2048): comm "test_progs", pid 44109, jiffies 4297131437 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 80 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc 9336483b): __kmalloc_noprof+0x3bf/0x560 __reuseport_alloc+0x1d/0x40 reuseport_alloc+0xca/0x150 reuseport_attach_prog+0x87/0x140 sk_reuseport_attach_bpf+0xc8/0x100 sk_setsockopt+0x1181/0x1990 do_sock_setsockopt+0x12b/0x160 __sys_setsockopt+0x7b/0xc0 __x64_sys_setsockopt+0x1b/0x30 do_syscall_64+0x93/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e
Fixes: 64d85290d79c ("bpf: Allow bpf_map_lookup_elem for SOCKMAP and SOCKHASH") Signed-off-by: Michal Luczaj mhal@rbox.co Reviewed-by: Martin KaFai Lau martin.lau@kernel.org Link: https://patch.msgid.link/20250110-reuseport-memleak-v1-1-fa1ddab0adfe@rbox.c... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/filter.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c index 34320ce70096a..5881944f1681c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -11190,6 +11190,7 @@ BPF_CALL_4(sk_select_reuseport, struct sk_reuseport_kern *, reuse_kern, bool is_sockarray = map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY; struct sock_reuseport *reuse; struct sock *selected_sk; + int err;
selected_sk = map->ops->map_lookup_elem(map, key); if (!selected_sk) @@ -11197,10 +11198,6 @@ BPF_CALL_4(sk_select_reuseport, struct sk_reuseport_kern *, reuse_kern,
reuse = rcu_dereference(selected_sk->sk_reuseport_cb); if (!reuse) { - /* Lookup in sock_map can return TCP ESTABLISHED sockets. */ - if (sk_is_refcounted(selected_sk)) - sock_put(selected_sk); - /* reuseport_array has only sk with non NULL sk_reuseport_cb. * The only (!reuse) case here is - the sk has already been * unhashed (e.g. by close()), so treat it as -ENOENT. @@ -11208,24 +11205,33 @@ BPF_CALL_4(sk_select_reuseport, struct sk_reuseport_kern *, reuse_kern, * Other maps (e.g. sock_map) do not provide this guarantee and * the sk may never be in the reuseport group to begin with. */ - return is_sockarray ? -ENOENT : -EINVAL; + err = is_sockarray ? -ENOENT : -EINVAL; + goto error; }
if (unlikely(reuse->reuseport_id != reuse_kern->reuseport_id)) { struct sock *sk = reuse_kern->sk;
- if (sk->sk_protocol != selected_sk->sk_protocol) - return -EPROTOTYPE; - else if (sk->sk_family != selected_sk->sk_family) - return -EAFNOSUPPORT; - - /* Catch all. Likely bound to a different sockaddr. */ - return -EBADFD; + if (sk->sk_protocol != selected_sk->sk_protocol) { + err = -EPROTOTYPE; + } else if (sk->sk_family != selected_sk->sk_family) { + err = -EAFNOSUPPORT; + } else { + /* Catch all. Likely bound to a different sockaddr. */ + err = -EBADFD; + } + goto error; }
reuse_kern->selected_sk = selected_sk;
return 0; +error: + /* Lookup in sock_map can return TCP ESTABLISHED sockets. */ + if (sk_is_refcounted(selected_sk)) + sock_put(selected_sk); + + return err; }
static const struct bpf_func_proto sk_select_reuseport_proto = {