[PATCH 7.1 402/438] drm/amdkfd: Fix missing authorization check in KFD_IOC_DBG_TRAP_DISABLE

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gang Ba <[email protected]>

commit 99b2fe4f19e3be0a8d0a0b5ea98d855970889653 upstream.

Prevent unauthorized termination of active GPU debug sessions.
Previously, users with /dev/kfd access could terminate another process's
debug session without proper ownership or ptrace authorization.

Signed-off-by: Gang Ba <[email protected]>
Reviewed-by: Kent Russell <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
(cherry picked from commit 4db4c5ffd5585b72622ecf6ffedf2da258ee23f5)
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -3038,10 +3038,14 @@ static int kfd_ioctl_set_debug_trap(stru
 		goto out;
 	}
 
-	/* Check if target is still PTRACED. */
+	/*
+	 * Verify debugger has permission to debug target process.
+	 * For cross-process debugging, require active ptrace relationship.
+	 * This applies to ALL operations to prevent unauthorized interference.
+	 */
 	rcu_read_lock();
-	if (target != p && args->op != KFD_IOC_DBG_TRAP_DISABLE
-				&& ptrace_parent(target->lead_thread) != current) {
+	if (target != p && ptrace_parent(target->lead_thread) != current
+			&& target->debugger_process != p) {
 		pr_err("PID %i is not PTRACED and cannot be debugged\n", args->pid);
 		r = -EPERM;
 	}