From 09a56edd479ae432315b1619928ae649cf14efcf Mon Sep 17 00:00:00 2001
From: Julian Orth <ju.orth@gmail.com>
Date: Wed, 1 Oct 2025 19:25:56 +0200
Subject: [PATCH] vulkan: enforce that dmabuf buffers are aligned to 4 bytes

---
 src/gfx_apis/vulkan.rs               | 2 ++
 src/gfx_apis/vulkan/dmabuf_buffer.rs | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/src/gfx_apis/vulkan.rs b/src/gfx_apis/vulkan.rs
index 1c512929..e0436747 100644
--- a/src/gfx_apis/vulkan.rs
+++ b/src/gfx_apis/vulkan.rs
@@ -223,6 +223,8 @@ pub enum VulkanError {
     GetFl(#[source] OsError),
     #[error("GBM implementation cannot be used with software renderer")]
     SoftwareRendererNotUsable,
+    #[error("DMABUF buffer offsets must be aligned to 4 bytes")]
+    DmaBufBufferOffsetAlignment,
 }
 
 impl From<VulkanError> for GfxError {
diff --git a/src/gfx_apis/vulkan/dmabuf_buffer.rs b/src/gfx_apis/vulkan/dmabuf_buffer.rs
index 3856ffd3..b8cf7ed1 100644
--- a/src/gfx_apis/vulkan/dmabuf_buffer.rs
+++ b/src/gfx_apis/vulkan/dmabuf_buffer.rs
@@ -16,6 +16,8 @@ use {
     uapi::OwnedFd,
 };
 
+pub(super) const TRANSFER_QUEUE_BUFFER_ALIGNMENT: u64 = 4;
+
 pub struct VulkanDmabufBuffer {
     pub(super) device: Rc<VulkanDevice>,
     pub(super) size: u64,
@@ -31,6 +33,9 @@ impl VulkanDevice {
         offset: u64,
         size: u64,
     ) -> Result<Rc<VulkanDmabufBuffer>, VulkanError> {
+        if offset % TRANSFER_QUEUE_BUFFER_ALIGNMENT != 0 {
+            return Err(VulkanError::DmaBufBufferOffsetAlignment);
+        }
         let mut memory_fd_properties = MemoryFdPropertiesKHR::default();
         unsafe {
             self.external_memory_fd