From 13c9e4ed125e19484234c960efe5ac9c55119523 Mon Sep 17 00:00:00 2001 From: Zack Rusin Date: Wed, 17 Sep 2025 11:36:55 -0400 Subject: [PATCH] drm/vmwgfx: Fix a null-ptr access in the cursor snooper [ Upstream commit 5ac2c0279053a2c5265d46903432fb26ae2d0da2 ] Check that the resource which is converted to a surface exists before trying to use the cursor snooper on it. vmw_cmd_res_check allows explicit invalid (SVGA3D_INVALID_ID) identifiers because some svga commands accept SVGA3D_INVALID_ID to mean "no surface", unfortunately functions that accept the actual surfaces as objects might (and in case of the cursor snooper, do not) be able to handle null objects. Make sure that we validate not only the identifier (via the vmw_cmd_res_check) but also check that the actual resource exists before trying to do something with it. Fixes unchecked null-ptr reference in the snooping code. Signed-off-by: Zack Rusin Fixes: c0951b797e7d ("drm/vmwgfx: Refactor resource management") Reported-by: Kuzey Arda Bulut Cc: Broadcom internal kernel review list Cc: dri-devel@lists.freedesktop.org Reviewed-by: Ian Forbes Link: https://lore.kernel.org/r/20250917153655.1968583-1-zack.rusin@broadcom.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c index ea741bc4ac3fc..8b72848bb25cd 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c @@ -1515,6 +1515,7 @@ static int vmw_cmd_dma(struct vmw_private *dev_priv, SVGA3dCmdHeader *header) { struct vmw_bo *vmw_bo = NULL; + struct vmw_resource *res; struct vmw_surface *srf = NULL; VMW_DECLARE_CMD_VAR(*cmd, SVGA3dCmdSurfaceDMA); int ret; @@ -1550,18 +1551,24 @@ static int vmw_cmd_dma(struct vmw_private *dev_priv, dirty = (cmd->body.transfer == SVGA3D_WRITE_HOST_VRAM) ? VMW_RES_DIRTY_SET : 0; - ret = vmw_cmd_res_check(dev_priv, sw_context, vmw_res_surface, - dirty, user_surface_converter, - &cmd->body.host.sid, NULL); + ret = vmw_cmd_res_check(dev_priv, sw_context, vmw_res_surface, dirty, + user_surface_converter, &cmd->body.host.sid, + NULL); if (unlikely(ret != 0)) { if (unlikely(ret != -ERESTARTSYS)) VMW_DEBUG_USER("could not find surface for DMA.\n"); return ret; } - srf = vmw_res_to_srf(sw_context->res_cache[vmw_res_surface].res); + res = sw_context->res_cache[vmw_res_surface].res; + if (!res) { + VMW_DEBUG_USER("Invalid DMA surface.\n"); + return -EINVAL; + } - vmw_kms_cursor_snoop(srf, sw_context->fp->tfile, &vmw_bo->tbo, header); + srf = vmw_res_to_srf(res); + vmw_kms_cursor_snoop(srf, sw_context->fp->tfile, &vmw_bo->tbo, + header); return 0; } -- 2.47.3