From b677b99db5c48ffd1eeef538b962080ac5fd65d9 Mon Sep 17 00:00:00 2001 From: Eduardo Lima Mitev Date: Fri, 28 Oct 2016 14:34:39 +0200 Subject: [PATCH] vulkan/wsi/x11: Fix behavior of vkGetPhysicalDeviceSurfacePresentModesKHR x11_surface_get_present_modes() is currently asserting that the number of elements in pPresentModeCount must be greater than or equal to the number of present modes available. This is buggy because pPresentModeCount elements are later copied from the internal modes' array, so if pPresentModeCount is greater, it will overflow it. On top of that, this assertion violates the spec. From the Vulkan 1.0 (revision 32, with KHR extensions), page 581 of the PDF: "If the value of pPresentModeCount is less than the number of presentation modes supported, at most pPresentModeCount values will be written. If pPresentModeCount is smaller than the number of presentation modes supported for the given surface, VK_INCOMPLETE will be returned instead of VK_SUCCESS to indicate that not all the available values were returned." So, the correct behavior is: if pPresentModeCount is greater than the internal number of formats, it is clamped to that many present modes. But if it is lesser than that, then pPresentModeCount elements are copied, and the call returns VK_INCOMPLETE. This fix is similar (but simpler and more readable) than the one I provided in 750d8cad72a for vkGetPhysicalDeviceSurfaceFormatsKHR, which was suffering from the same problem. Reviewed-by: Eric Engestrom --- src/vulkan/wsi/wsi_common_x11.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/vulkan/wsi/wsi_common_x11.c b/src/vulkan/wsi/wsi_common_x11.c index efd3fb55299..4a232f5213b 100644 --- a/src/vulkan/wsi/wsi_common_x11.c +++ b/src/vulkan/wsi/wsi_common_x11.c @@ -418,11 +418,11 @@ x11_surface_get_present_modes(VkIcdSurfaceBase *surface, return VK_SUCCESS; } - assert(*pPresentModeCount >= ARRAY_SIZE(present_modes)); + *pPresentModeCount = MIN2(*pPresentModeCount, ARRAY_SIZE(present_modes)); typed_memcpy(pPresentModes, present_modes, *pPresentModeCount); - *pPresentModeCount = ARRAY_SIZE(present_modes); - return VK_SUCCESS; + return *pPresentModeCount < ARRAY_SIZE(present_modes) ? + VK_INCOMPLETE : VK_SUCCESS; } VkResult wsi_create_xcb_surface(const VkAllocationCallbacks *pAllocator, -- 2.30.2