Commit 129d868e authored by Kees Cook's avatar Kees Cook Committed by Daniel Borkmann

bpf: Replace 0-length arrays with flexible arrays

Zero-length arrays are deprecated [1]. Replace struct bpf_array's union
of 0-length arrays with flexible arrays. Detected with GCC 13, by using
-fstrict-flex-arrays=3:

  arch/x86/net/bpf_jit_comp.c: In function 'bpf_tail_call_direct_fixup':
  arch/x86/net/bpf_jit_comp.c:606:37: warning: array subscript <unknown> is outside array bounds of 'void *[0]' [-Warray-bounds=]
    606 |                 target = array->ptrs[poke->tail_call.key];
        |                          ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
  In file included from include/linux/filter.h:9,
                   from arch/x86/net/bpf_jit_comp.c:9:
  include/linux/bpf.h:1527:23: note: while referencing 'ptrs'
   1527 |                 void *ptrs[0] __aligned(8);
        |                       ^~~~

  [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arraysSigned-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230105192646.never.154-kees@kernel.org
parent af0e26be
...@@ -1523,9 +1523,9 @@ struct bpf_array { ...@@ -1523,9 +1523,9 @@ struct bpf_array {
u32 index_mask; u32 index_mask;
struct bpf_array_aux *aux; struct bpf_array_aux *aux;
union { union {
char value[0] __aligned(8); DECLARE_FLEX_ARRAY(char, value) __aligned(8);
void *ptrs[0] __aligned(8); DECLARE_FLEX_ARRAY(void *, ptrs) __aligned(8);
void __percpu *pptrs[0] __aligned(8); DECLARE_FLEX_ARRAY(void __percpu *, pptrs) __aligned(8);
}; };
}; };
......
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