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Commit 6b173873 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by David S. Miller
Browse files

bpf: recognize 64bit immediate loads as consts 



When running as parser interpret BPF_LD | BPF_IMM | BPF_DW
instructions as loading CONST_IMM with the value stored
in imm.  The verifier will continue not recognizing those
due to concerns about search space/program complexity
increase.

Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 13a27dfc

kernel/bpf/verifier.c

+12 −2
Original line number Diff line number Diff line
@@ -1769,10 +1769,20 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) 
	if (err)

		return err;



	if (insn->src_reg == 0)

		/* generic move 64-bit immediate into a register */

	if (insn->src_reg == 0) {

		/* generic move 64-bit immediate into a register,

		 * only analyzer needs to collect the ld_imm value.

		 */

		u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;



		if (!env->analyzer_ops)

			return 0;



		regs[insn->dst_reg].type = CONST_IMM;

		regs[insn->dst_reg].imm = imm;

		return 0;

	}



	/* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */

	BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);