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vsock: Keep the binding until socket destruction

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Preserve sockets bindings; this includes both resulting from an explicit
bind() and those implicitly bound through autobind during connect().

Prevents socket unbinding during a transport reassignment, which fixes a
use-after-free:

    1. vsock_create() (refcnt=1) calls vsock_insert_unbound() (refcnt=2)
    2. transport->release() calls vsock_remove_bound() without checking if
       sk was bound and moved to bound list (refcnt=1)
    3. vsock_bind() assumes sk is in unbound list and before
       __vsock_insert_bound(vsock_bound_sockets()) calls
       __vsock_remove_bound() which does:
           list_del_init(&vsk->bound_table); // nop
           sock_put(&vsk->sk);               // refcnt=0

BUG: KASAN: slab-use-after-free in __vsock_bind+0x62e/0x730
Read of size 4 at addr ffff88816b46a74c by task a.out/2057
 dump_stack_lvl+0x68/0x90
 print_report+0x174/0x4f6
 kasan_report+0xb9/0x190
 __vsock_bind+0x62e/0x730
 vsock_bind+0x97/0xe0
 __sys_bind+0x154/0x1f0
 __x64_sys_bind+0x6e/0xb0
 do_syscall_64+0x93/0x1b0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Allocated by task 2057:
 kasan_save_stack+0x1e/0x40
 kasan_save_track+0x10/0x30
 __kasan_slab_alloc+0x85/0x90
 kmem_cache_alloc_noprof+0x131/0x450
 sk_prot_alloc+0x5b/0x220
 sk_alloc+0x2c/0x870
 __vsock_create.constprop.0+0x2e/0xb60
 vsock_create+0xe4/0x420
 __sock_create+0x241/0x650
 __sys_socket+0xf2/0x1a0
 __x64_sys_socket+0x6e/0xb0
 do_syscall_64+0x93/0x1b0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Freed by task 2057:
 kasan_save_stack+0x1e/0x40
 kasan_save_track+0x10/0x30
 kasan_save_free_info+0x37/0x60
 __kasan_slab_free+0x4b/0x70
 kmem_cache_free+0x1a1/0x590
 __sk_destruct+0x388/0x5a0
 __vsock_bind+0x5e1/0x730
 vsock_bind+0x97/0xe0
 __sys_bind+0x154/0x1f0
 __x64_sys_bind+0x6e/0xb0
 do_syscall_64+0x93/0x1b0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

refcount_t: addition on 0; use-after-free.
WARNING: CPU: 7 PID: 2057 at lib/refcount.c:25 refcount_warn_saturate+0xce/0x150
RIP: 0010:refcount_warn_saturate+0xce/0x150
 __vsock_bind+0x66d/0x730
 vsock_bind+0x97/0xe0
 __sys_bind+0x154/0x1f0
 __x64_sys_bind+0x6e/0xb0
 do_syscall_64+0x93/0x1b0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

refcount_t: underflow; use-after-free.
WARNING: CPU: 7 PID: 2057 at lib/refcount.c:28 refcount_warn_saturate+0xee/0x150
RIP: 0010:refcount_warn_saturate+0xee/0x150
 vsock_remove_bound+0x187/0x1e0
 __vsock_release+0x383/0x4a0
 vsock_release+0x90/0x120
 __sock_release+0xa3/0x250
 sock_close+0x14/0x20
 __fput+0x359/0xa80
 task_work_run+0x107/0x1d0
 do_exit+0x847/0x2560
 do_group_exit+0xb8/0x250
 __x64_sys_exit_group+0x3a/0x50
 x64_sys_call+0xfec/0x14f0
 do_syscall_64+0x93/0x1b0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Fixes: c0cfa2d8a7 ("vsock: add multi-transports support")
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://patch.msgid.link/20250128-vsock-transport-vs-autobind-v3-1-1cf57065b770@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Michal Luczaj 2025-01-28 14:15:27 +01:00 • committed by Jakub Kicinski
parent 9e6c4e6b60
commit fcdd2242c0
1 changed files with 6 additions and 2 deletions
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8
net/vmw_vsock/af_vsock.c
View file

@ -337,7 +337,10 @@ EXPORT_SYMBOL_GPL(vsock_find_connected_socket);
void vsock_remove_sock(struct vsock_sock *vsk)
{
vsock_remove_bound(vsk);
/* Transport reassignment must not remove the binding. */
if (sock_flag(sk_vsock(vsk), SOCK_DEAD))
vsock_remove_bound(vsk);
vsock_remove_connected(vsk);
}
EXPORT_SYMBOL_GPL(vsock_remove_sock);
@ -821,12 +824,13 @@ static void __vsock_release(struct sock *sk, int level)
*/
lock_sock_nested(sk, level);
sock_orphan(sk);
if (vsk->transport)
vsk->transport->release(vsk);
else if (sock_type_connectible(sk->sk_type))
vsock_remove_sock(vsk);
sock_orphan(sk);
sk->sk_shutdown = SHUTDOWN_MASK;
skb_queue_purge(&sk->sk_receive_queue);