From f7c68d51890dd2f3ab61a94529602c4d1addccd3 Mon Sep 17 00:00:00 2001
From: Egor Lazarchuk <yegorlz@amazon.co.uk>
Date: Mon, 9 Dec 2024 11:09:43 +0000
Subject: [PATCH] This is a combination of 2 commits.

fix: use correct ioctl wrapper for `create_device`

Use `ioctl_with_mut_ref` instead of `ioctl_with_ref`
in the `create_device` method as it needs to write to the
`kvm_create_device` struct passed to it. This incorrect
usage of `ioctl_with_ref` causes newer versions of Rust compiler
(1.82 and above) to treat the `kvm_create_device` struct as read-only
and bypass following reads from it. This optimization lead to incorrect
value being passed to the `File::from_raw_fd` call.

Signed-off-by: Egor Lazarchuk <yegorlz@amazon.co.uk>
---
 kvm-ioctls/CHANGELOG.md     | 6 ++++++
 kvm-ioctls/src/ioctls/vm.rs | 8 ++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/kvm-ioctls/CHANGELOG.md b/kvm-ioctls/CHANGELOG.md
index 526bef11..a8affafd 100644
--- a/kvm-ioctls/CHANGELOG.md
+++ b/kvm-ioctls/CHANGELOG.md
@@ -7,6 +7,12 @@
 - [[#288](https://github.com/rust-vmm/kvm-ioctls/pull/288)]: Introduce `Cap::GuestMemfd`, `Cap::MemoryAttributes` and 
    `Cap::UserMemory2` capabilities enum variants for use with `VmFd::check_extension`.
 
+### Fixed
+
+- [[#298](https://github.com/rust-vmm/kvm/pull/298)]: Fixed incorrect usage of `ioctl_wit_ref` in the
+  `create_device` method. Replace it with `ioctl_wit_mut_ref` as the passed parameter may be mutated by the
+  ioctl.
+
 ## v0.19.0
 
 ### Added
diff --git a/kvm-ioctls/src/ioctls/vm.rs b/kvm-ioctls/src/ioctls/vm.rs
index edc63e41..d293c6ad 100644
--- a/kvm-ioctls/src/ioctls/vm.rs
+++ b/kvm-ioctls/src/ioctls/vm.rs
@@ -22,11 +22,11 @@ use crate::ioctls::{KvmRunWrapper, Result};
 use crate::kvm_ioctls::*;
 use vmm_sys_util::errno;
 use vmm_sys_util::eventfd::EventFd;
+#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
+use vmm_sys_util::ioctl::ioctl;
 #[cfg(target_arch = "x86_64")]
 use vmm_sys_util::ioctl::ioctl_with_mut_ptr;
-#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
-use vmm_sys_util::ioctl::{ioctl, ioctl_with_mut_ref};
-use vmm_sys_util::ioctl::{ioctl_with_ref, ioctl_with_val};
+use vmm_sys_util::ioctl::{ioctl_with_mut_ref, ioctl_with_ref, ioctl_with_val};
 
 /// An address either in programmable I/O space or in memory mapped I/O space.
 ///
@@ -1300,7 +1300,7 @@ impl VmFd {
     /// ```
     pub fn create_device(&self, device: &mut kvm_create_device) -> Result<DeviceFd> {
         // SAFETY: Safe because we are calling this with the VM fd and we trust the kernel.
-        let ret = unsafe { ioctl_with_ref(self, KVM_CREATE_DEVICE(), device) };
+        let ret = unsafe { ioctl_with_mut_ref(self, KVM_CREATE_DEVICE(), device) };
         if ret == 0 {
             // SAFETY: We validated the return of the function creating the fd and we trust the
             // kernel.