drm/xe/oa: Limit num_syncs to prevent oversized allocations

The OA open parameters did not validate num_syncs, allowing
userspace to pass arbitrarily large values, potentially
leading to excessive allocations.

Add check to ensure that num_syncs does not exceed DRM_XE_MAX_SYNCS,
returning -EINVAL when the limit is violated.

v2: use XE_IOCTL_DBG() and drop duplicated check. (Ashutosh)

Fixes: c8507a2 ("drm/xe/oa/uapi: Define and parse OA sync properties")
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20251205234715.2476561-6-shuicheng.lin@intel.com
(cherry picked from commit e057b2d)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

Author: ShuichengLin

drivers/gpu/drm/xe/xe_oa.c

@@ -1254,6 +1254,9 @@ static int xe_oa_set_no_preempt(struct xe_oa *oa, u64 value,
 static int xe_oa_set_prop_num_syncs(struct xe_oa *oa, u64 value,
 				    struct xe_oa_open_param *param)
 {
+	if (XE_IOCTL_DBG(oa->xe, value > DRM_XE_MAX_SYNCS))
+		return -EINVAL;
+
 	param->num_syncs = value;
 	return 0;
 }