bpf: fix bpf_tail_call() x64 JIT (90caccdd) · Commits · 戴 / test

- bpf prog_array just like all other types of bpf array accepts 32-bit index. Clarify that in the comment. - fix x64 JIT of bpf_tail_call which was incorrectly loading 8 instead of 4 bytes - tighten corresponding check in the interpreter to stay consistent The JIT bug can be triggered after introduction of BPF_F_NUMA_NODE flag in commit in 4.14. Before that the map_flags would stay zero and though JIT code is wrong it will check bounds correctly. Hence two fixes tags. All other JITs don't have this problem. Signed-off-by:

Alexei Starovoitov <ast@kernel.org> Fixes: ("bpf: Allow selecting numa node during map creation") Fixes: ("x86: bpf_jit: implement bpf_tail_call() helper") Acked-by:

Daniel Borkmann <daniel@iogearbox.net> Acked-by:

Martin KaFai Lau <kafai@fb.com> Reviewed-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

arch/x86/net/bpf_jit_comp.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -284,9 +284,9 @@ static void emit_bpf_tail_call(u8 **pprog)
		/* if (index >= array->map.max_entries)
		* goto out;
		*/
		EMIT4(0x48, 0x8B, 0x46, /* mov rax, qword ptr [rsi + 16] */
		EMIT2(0x89, 0xD2); /* mov edx, edx */
		EMIT3(0x39, 0x56, /* cmp dword ptr [rsi + 16], edx */
		offsetof(struct bpf_array, map.max_entries));
		EMIT3(0x48, 0x39, 0xD0); /* cmp rax, rdx */
		#define OFFSET1 43 /* number of bytes to jump */
		EMIT2(X86_JBE, OFFSET1); /* jbe out */
		label1 = cnt;

include/uapi/linux/bpf.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -312,7 +312,7 @@ union bpf_attr {
		* jump into another BPF program
		* @ctx: context pointer passed to next program
		* @prog_array_map: pointer to map which type is BPF_MAP_TYPE_PROG_ARRAY
		* @index: index inside array that selects specific program to run
		* @index: 32-bit index inside array that selects specific program to run
		* Return: 0 on success or negative error
		*
		* int bpf_clone_redirect(skb, ifindex, flags)

kernel/bpf/core.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1022,7 +1022,7 @@ select_insn:
		struct bpf_map map = (struct bpf_map ) (unsigned long) BPF_R2;
		struct bpf_array *array = container_of(map, struct bpf_array, map);
		struct bpf_prog *prog;
		u64 index = BPF_R3;
		u32 index = BPF_R3;

		if (unlikely(index >= array->map.max_entries))
		goto out;

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