kernel: Fixed potential null pointer issue with current->mm in kernel version 5.10

When calling get_full_comm() within system call hooks, current->mm may be null (prctl). A fallback mechanism for current->comm must be added beforehand to prevent null pointer dereferences when accessing mm->arg_start/arg_end.

Signed-off-by: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>

kernel/manual_su.h

@@ -9,6 +9,8 @@
 #define mmap_lock mmap_sem
 #endif
 
+#define ksu_task_is_dead(t) ((t)->exit_state != 0)
+
 #define MAX_PENDING 16
 #define REMOVE_DELAY_CALLS 150
 #define MAX_TOKENS 10