tools/testing/selftests/bpf/progs/lru_bug.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <vmlinux.h>
   3 #include <bpf/bpf_tracing.h>
   4 #include <bpf/bpf_helpers.h>
   5
   6 struct map_value {
   7         struct task_struct __kptr_untrusted *ptr;
   8 };
   9
  10 struct {
  11         __uint(type, BPF_MAP_TYPE_LRU_HASH);
  12         __uint(max_entries, 1);
  13         __type(key, int);
  14         __type(value, struct map_value);
  15 } lru_map SEC(".maps");
  16
  17 int pid = 0;
  18 int result = 1;
  19
  20 SEC("fentry/bpf_ktime_get_ns")
  21 int printk(void *ctx)
  22 {
  23         struct map_value v = {};
  24
  25         if (pid == bpf_get_current_task_btf()->pid)
  26                 bpf_map_update_elem(&lru_map, &(int){0}, &v, 0);
  27         return 0;
  28 }
  29
  30 SEC("fentry/do_nanosleep")
  31 int nanosleep(void *ctx)
  32 {
  33         struct map_value val = {}, *v;
  34         struct task_struct *current;
  35
  36         bpf_map_update_elem(&lru_map, &(int){0}, &val, 0);
  37         v = bpf_map_lookup_elem(&lru_map, &(int){0});
  38         if (!v)
  39                 return 0;
  40         bpf_map_delete_elem(&lru_map, &(int){0});
  41         current = bpf_get_current_task_btf();
  42         v->ptr = current;
  43         pid = current->pid;
  44         bpf_ktime_get_ns();
  45         result = !v->ptr;
  46         return 0;
  47 }
  48
  49 char _license[] SEC("license") = "GPL";