UPSTREAM: net: socket: set sock->sk to NULL after calling proto_ops::release()

Commit 9060cb719e61 ("net: crypto set sk to NULL when af_alg_release.")
fixed a use-after-free in sockfs_setattr() when an AF_ALG socket is
closed concurrently with fchownat().  However, it ignored that many
other proto_ops::release() methods don't set sock->sk to NULL and
therefore allow the same use-after-free:

    - base_sock_release
    - bnep_sock_release
    - cmtp_sock_release
    - data_sock_release
    - dn_release
    - hci_sock_release
    - hidp_sock_release
    - iucv_sock_release
    - l2cap_sock_release
    - llcp_sock_release
    - llc_ui_release
    - rawsock_release
    - rfcomm_sock_release
    - sco_sock_release
    - svc_release
    - vcc_release
    - x25_release

Rather than fixing all these and relying on every socket type to get
this right forever, just make __sock_release() set sock->sk to NULL
itself after calling proto_ops::release().

Reproducer that produces the KASAN splat when any of these socket types
are configured into the kernel:

    #include <pthread.h>
    #include <stdlib.h>
    #include <sys/socket.h>
    #include <unistd.h>

    pthread_t t;
    volatile int fd;

    void *close_thread(void *arg)
        for (;;) {
            usleep(rand() % 100);

    int main()
        pthread_create(&t, NULL, close_thread, NULL);
        for (;;) {
            fd = socket(rand() % 50, rand() % 11, 0);
            fchownat(fd, "", 1000, 1000, 0x1000);

Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.")
Signed-off-by: Eric Biggers <>
Acked-by: Cong Wang <>
Signed-off-by: David S. Miller <>

(cherry picked from commit ff7b11aa481f682e0e9711abfeb7d03f5cd612bf)
Bug: 125367761
Test: used reproducer above
Change-Id: Ied4bbca5c7eb80c201fec6e0aabc95c24acc1b59
Signed-off-by: Eric Biggers <>
1 file changed