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@xxxxxxx>
---
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 834614071727ab92cee759dc788ec2ee6f92284b..2fb45a86f3ddbffa9fd55885d4c4c0d8c3a6c381 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -11251,6 +11251,7 @@ 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)
@@ -11258,10 +11259,6 @@ 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.
@@ -11269,24 +11266,33 @@ 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 = {
---
base-commit: 1f6ff8756091d99b7e5fa556abc0465328302b8b
change-id: 20250110-reuseport-memleak-9ac6587bd99a
Best regards,
--
Michal Luczaj <mhal@xxxxxxx>
