From 21bc51cb89ced74d6645a138cc2f21184bc75094 Mon Sep 17 00:00:00 2001 From: Zack Rusin Date: Sun, 9 Aug 2026 16:45:15 -0400 Subject: [PATCH] drm/vmwgfx: validate pitch coming from userspace Validate the pitch, alongside the box dimensions before trying to copy data from the underlying surface. Fixes possible out of bounds reads with cursor snooping. Fixes: 2ac863719e51 ("vmwgfx: Snoop DMA transfers with non-covering sizes") Cc: stable@vger.kernel.org Reported-by: Youness HFA Signed-off-by: Zack Rusin Reviewed-by: Maaz Mombasawala Link: https://patch.msgid.link/20260809204515.211045-1-zack.rusin@broadcom.com --- drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c | 26 ++++++++++++++++---- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c b/drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c index d1e7df500190..5a69606a0593 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c @@ -324,6 +324,7 @@ void vmw_kms_cursor_snoop(struct vmw_surface *srf, unsigned long kmap_num; SVGA3dCopyBox *box; u32 box_count; + u64 src_extent; void *virtual; bool is_iomem; struct vmw_dma_cmd { @@ -335,6 +336,8 @@ void vmw_kms_cursor_snoop(struct vmw_surface *srf, vmw_surface_get_desc(VMW_CURSOR_SNOOP_FORMAT); const u32 image_pitch = VMW_CURSOR_SNOOP_WIDTH * desc->pitchBytesPerBlock; + BUILD_BUG_ON(sizeof(*srf->snooper.image) != desc->pitchBytesPerBlock); + cmd = container_of(header, struct vmw_dma_cmd, header); /* No snooper installed, nothing to copy */ @@ -372,8 +375,19 @@ void vmw_kms_cursor_snoop(struct vmw_surface *srf, return; } + if (box->w == 0 || box->h == 0) + return; + + src_extent = (u64)(box->h - 1) * cmd->dma.guest.pitch + + (u64)box->w * desc->pitchBytesPerBlock; + if (src_extent > bo->base.size) { + DRM_ERROR("Cursor snoop source of %llu bytes exceeds the %zu byte buffer\n", + src_extent, bo->base.size); + return; + } + kmap_offset = cmd->dma.guest.ptr.offset >> PAGE_SHIFT; - kmap_num = (VMW_CURSOR_SNOOP_HEIGHT * image_pitch) >> PAGE_SHIFT; + kmap_num = PFN_UP(src_extent); ret = ttm_bo_reserve(bo, true, false, NULL); if (unlikely(ret != 0)) { @@ -387,14 +401,16 @@ void vmw_kms_cursor_snoop(struct vmw_surface *srf, virtual = ttm_kmap_obj_virtual(&map, &is_iomem); - if (box->w == VMW_CURSOR_SNOOP_WIDTH && cmd->dma.guest.pitch == image_pitch) { + if (box->w == VMW_CURSOR_SNOOP_WIDTH && + box->h == VMW_CURSOR_SNOOP_HEIGHT && + cmd->dma.guest.pitch == image_pitch) { memcpy(srf->snooper.image, virtual, VMW_CURSOR_SNOOP_HEIGHT * image_pitch); } else { - /* Image is unsigned pointer. */ + /* The destination stride is in pixels. */ for (i = 0; i < box->h; i++) - memcpy(srf->snooper.image + i * image_pitch, - virtual + i * cmd->dma.guest.pitch, + memcpy(srf->snooper.image + i * VMW_CURSOR_SNOOP_WIDTH, + virtual + (size_t)i * cmd->dma.guest.pitch, box->w * desc->pitchBytesPerBlock); } srf->snooper.id++;