[PATCH] drm/xe: Protect devcoredump_free

[Rodrigo Vivi]

While we don't have the full flow protection when devcoredump
is accessed after device unbind. Let's at least for now
protect against null dereference:

[  422.766508] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
[  423.119584] RIP: 0010:xe_vm_snapshot_free+0x30/0x180 [xe]

While at it, I also fixed a non-standard code-declaration block
on the similar function of xe_guc_submit.

Fixes: e5f661bb56d4 ("drm/xe/devcoredump: Print errno if VM snapshot was not captured")
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/xe/xe_guc_submit.c | 1 +
 drivers/gpu/drm/xe/xe_vm.c         | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index f42f1b567067..6e32f9ce4eb5 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1961,6 +1961,7 @@ xe_guc_exec_queue_snapshot_print(struct xe_guc_submit_exec_queue_snapshot *snaps
 void xe_guc_exec_queue_snapshot_free(struct xe_guc_submit_exec_queue_snapshot *snapshot)
 {
 	int i;
+
 	if (!snapshot)
 		return;
 
diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index f4bfb2705956..ccb2e1c67c2c 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -3514,7 +3514,7 @@ void xe_vm_snapshot_free(struct xe_vm_snapshot *snap)
 {
 	unsigned long i;
 
-	if (IS_ERR(snap))
+	if (!snap || IS_ERR(snap))
 		return;
 
 	for (i = 0; i < snap->num_snaps; i++) {
-- 
2.44.0