On Wed, Feb 05, 2025 at 02:44:46PM +0100, Greg Kroah-Hartman wrote:
6.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michal Luczaj <mhal@xxxxxxx>
[ Upstream commit fcdd2242c0231032fc84e1404315c245ae56322a ]
Hi Greg,
This patch introduced a bug[1], Michal has already sent a patch to fix
it [2], but has not been merged yet. Should we wait and merge them
together? WDYT?
Thanks,
Luigi
[1]https://lore.kernel.org/all/67a09300.050a0220.d7c5a.008b.GAE@xxxxxxxxxx/
[2]https://lore.kernel.org/all/20250206-vsock-linger-nullderef-v2-0-f8a1f19146f8@xxxxxxx/
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: c0cfa2d8a788 ("vsock: add multi-transports support")
Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
Signed-off-by: Michal Luczaj <mhal@xxxxxxx>
Link: https://patch.msgid.link/20250128-vsock-transport-vs-autobind-v3-1-1cf57065b770@xxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/vmw_vsock/af_vsock.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index fa9d1b49599bf..cfe18bc8fdbe7 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -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);
--
2.39.5
