Re: [syzbot] Re: [syzbot] [kernel?] KMSAN: kernel-infoleak in vmci_host_unlocked_ioctl (3)

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Subject: Re: [syzbot] [kernel?] KMSAN: kernel-infoleak in vmci_host_unlocked_ioctl (3)
Author: lizhi.xu@xxxxxxxxxxxxx

#syz test

diff --git a/drivers/misc/vmw_vmci/vmci_host.c b/drivers/misc/vmw_vmci/vmci_host.c
index b64944367ac5..178febf6c561 100644
--- a/drivers/misc/vmw_vmci/vmci_host.c
+++ b/drivers/misc/vmw_vmci/vmci_host.c
@@ -385,14 +385,20 @@ static int vmci_host_do_send_datagram(struct vmci_host_dev *vmci_host_dev,
 		return -EINVAL;
 	}
 
-	dg = memdup_user((void __user *)(uintptr_t)send_info.addr,
-			 send_info.len);
-	if (IS_ERR(dg)) {
+	dg = kzalloc(send_info.len, GFP_KERNEL);
+
+	if (IS_ERR_OR_NULL(dg)) {
 		vmci_ioctl_err(
 			"cannot allocate memory to dispatch datagram\n");
 		return PTR_ERR(dg);
 	}
 
+	if (copy_from_user(dg, (void __user *)(uintptr_t)send_info.addr, send_info.len)) {
+		vmci_ioctl_err("copy datagram fails\n");
+		kfree(dg);
+		return -EFAULT;
+	}
+
 	if (VMCI_DG_SIZE(dg) != send_info.len) {
 		vmci_ioctl_err("datagram size mismatch\n");
 		kfree(dg);