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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 | // SPDX-License-Identifier: GPL-2.0 #include <vmlinux.h> #include <bpf/bpf_tracing.h> #include <bpf/bpf_helpers.h> struct map_value { struct prog_test_ref_kfunc __kptr_ref *ptr; }; struct { __uint(type, BPF_MAP_TYPE_ARRAY); __type(key, int); __type(value, struct map_value); __uint(max_entries, 16); } array_map SEC(".maps"); extern struct prog_test_ref_kfunc *bpf_kfunc_call_test_acquire(unsigned long *sp) __ksym; extern void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) __ksym; static __noinline int cb1(void *map, void *key, void *value, void *ctx) { void *p = *(void **)ctx; bpf_kfunc_call_test_release(p); /* Without the fix this would cause underflow */ return 0; } SEC("?tc") int underflow_prog(void *ctx) { struct prog_test_ref_kfunc *p; unsigned long sl = 0; p = bpf_kfunc_call_test_acquire(&sl); if (!p) return 0; bpf_for_each_map_elem(&array_map, cb1, &p, 0); return 0; } static __always_inline int cb2(void *map, void *key, void *value, void *ctx) { unsigned long sl = 0; *(void **)ctx = bpf_kfunc_call_test_acquire(&sl); /* Without the fix this would leak memory */ return 0; } SEC("?tc") int leak_prog(void *ctx) { struct prog_test_ref_kfunc *p; struct map_value *v; unsigned long sl; v = bpf_map_lookup_elem(&array_map, &(int){0}); if (!v) return 0; p = NULL; bpf_for_each_map_elem(&array_map, cb2, &p, 0); p = bpf_kptr_xchg(&v->ptr, p); if (p) bpf_kfunc_call_test_release(p); return 0; } static __always_inline int cb(void *map, void *key, void *value, void *ctx) { return 0; } static __always_inline int cb3(void *map, void *key, void *value, void *ctx) { unsigned long sl = 0; void *p; bpf_kfunc_call_test_acquire(&sl); bpf_for_each_map_elem(&array_map, cb, &p, 0); /* It should only complain here, not in cb. This is why we need * callback_ref to be set to frameno. */ return 0; } SEC("?tc") int nested_cb(void *ctx) { struct prog_test_ref_kfunc *p; unsigned long sl = 0; int sp = 0; p = bpf_kfunc_call_test_acquire(&sl); if (!p) return 0; bpf_for_each_map_elem(&array_map, cb3, &sp, 0); bpf_kfunc_call_test_release(p); return 0; } SEC("?tc") int non_cb_transfer_ref(void *ctx) { struct prog_test_ref_kfunc *p; unsigned long sl = 0; p = bpf_kfunc_call_test_acquire(&sl); if (!p) return 0; cb1(NULL, NULL, NULL, &p); bpf_kfunc_call_test_acquire(&sl); return 0; } char _license[] SEC("license") = "GPL"; |