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Subject[PATCH] drm/vmwgfx: avoid null pointer dereference at failure paths
Date
vmw_takedown_otable_base() and vmw_mob_unbind() check for
potential vmw_fifo_reserve() failure and print error message,
but then immediately dereference NULL pointer.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
---
drivers/gpu/drm/vmwgfx/vmwgfx_mob.c | 35 +++++++++++++++++++----------------
1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
index d4a5a19cb8c3..04a64b8cd3cd 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
@@ -188,18 +188,20 @@ static void vmw_takedown_otable_base(struct vmw_private *dev_priv,

bo = otable->page_table->pt_bo;
cmd = vmw_fifo_reserve(dev_priv, sizeof(*cmd));
- if (unlikely(cmd == NULL))
- DRM_ERROR("Failed reserving FIFO space for OTable setup.\n");
-
- memset(cmd, 0, sizeof(*cmd));
- cmd->header.id = SVGA_3D_CMD_SET_OTABLE_BASE;
- cmd->header.size = sizeof(cmd->body);
- cmd->body.type = type;
- cmd->body.baseAddress = 0;
- cmd->body.sizeInBytes = 0;
- cmd->body.validSizeInBytes = 0;
- cmd->body.ptDepth = SVGA3D_MOBFMT_INVALID;
- vmw_fifo_commit(dev_priv, sizeof(*cmd));
+ if (unlikely(cmd == NULL)) {
+ DRM_ERROR("Failed reserving FIFO space for OTable "
+ "takedown.\n");
+ } else {
+ memset(cmd, 0, sizeof(*cmd));
+ cmd->header.id = SVGA_3D_CMD_SET_OTABLE_BASE;
+ cmd->header.size = sizeof(cmd->body);
+ cmd->body.type = type;
+ cmd->body.baseAddress = 0;
+ cmd->body.sizeInBytes = 0;
+ cmd->body.validSizeInBytes = 0;
+ cmd->body.ptDepth = SVGA3D_MOBFMT_INVALID;
+ vmw_fifo_commit(dev_priv, sizeof(*cmd));
+ }

if (bo) {
int ret;
@@ -562,11 +564,12 @@ void vmw_mob_unbind(struct vmw_private *dev_priv,
if (unlikely(cmd == NULL)) {
DRM_ERROR("Failed reserving FIFO space for Memory "
"Object unbinding.\n");
+ } else {
+ cmd->header.id = SVGA_3D_CMD_DESTROY_GB_MOB;
+ cmd->header.size = sizeof(cmd->body);
+ cmd->body.mobid = mob->id;
+ vmw_fifo_commit(dev_priv, sizeof(*cmd));
}
- cmd->header.id = SVGA_3D_CMD_DESTROY_GB_MOB;
- cmd->header.size = sizeof(cmd->body);
- cmd->body.mobid = mob->id;
- vmw_fifo_commit(dev_priv, sizeof(*cmd));
if (bo) {
vmw_fence_single_bo(bo, NULL);
ttm_bo_unreserve(bo);
--
1.8.3.2


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