From: Michal Luczaj <mhal@rbox.co> stable inclusion from stable-v6.6.99 commit 9d24bb6780282b0255b9929abe5e8f98007e2c6e category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/13525 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 687aa0c5581b8d4aa87fd92973e4ee576b550cdf ] Transport assignment may race with module unload. Protect new_transport from becoming a stale pointer. This also takes care of an insecure call in vsock_use_local_transport(); add a lockdep assert. BUG: unable to handle page fault for address: fffffbfff8056000 Oops: Oops: 0000 [#1] SMP KASAN RIP: 0010:vsock_assign_transport+0x366/0x600 Call Trace: vsock_connect+0x59c/0xc40 __sys_connect+0xe8/0x100 __x64_sys_connect+0x6e/0xc0 do_syscall_64+0x92/0x1c0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Fixes: c0cfa2d8a788 ("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/20250703-vsock-transports-toctou-v4-2-98f0eb530747@... Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/vmw_vsock/af_vsock.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index dc62b30c0be5..58b7404a0da0 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -406,6 +406,8 @@ EXPORT_SYMBOL_GPL(vsock_enqueue_accept); static bool vsock_use_local_transport(unsigned int remote_cid) { + lockdep_assert_held(&vsock_register_mutex); + if (!transport_local) return false; @@ -463,6 +465,8 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) remote_flags = vsk->remote_addr.svm_flags; + mutex_lock(&vsock_register_mutex); + switch (sk->sk_type) { case SOCK_DGRAM: new_transport = transport_dgram; @@ -478,12 +482,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) new_transport = transport_h2g; break; default: - return -ESOCKTNOSUPPORT; + ret = -ESOCKTNOSUPPORT; + goto err; } if (vsk->transport) { - if (vsk->transport == new_transport) - return 0; + if (vsk->transport == new_transport) { + ret = 0; + goto err; + } /* transport->release() must be called with sock lock acquired. * This path can only be taken during vsock_connect(), where we @@ -507,8 +514,16 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) /* We increase the module refcnt to prevent the transport unloading * while there are open sockets assigned to it. */ - if (!new_transport || !try_module_get(new_transport->module)) - return -ENODEV; + if (!new_transport || !try_module_get(new_transport->module)) { + ret = -ENODEV; + goto err; + } + + /* It's safe to release the mutex after a successful try_module_get(). + * Whichever transport `new_transport` points at, it won't go away until + * the last module_put() below or in vsock_deassign_transport(). + */ + mutex_unlock(&vsock_register_mutex); if (sk->sk_type == SOCK_SEQPACKET) { if (!new_transport->seqpacket_allow || @@ -527,6 +542,9 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) vsk->transport = new_transport; return 0; +err: + mutex_unlock(&vsock_register_mutex); + return ret; } EXPORT_SYMBOL_GPL(vsock_assign_transport); -- 2.25.1