Commit 138cc42c authored May 06, 2024 by Cupertino Miranda Committed by Alexei Starovoitov May 06, 2024

bpf/verifier: improve XOR and OR range computation



Range for XOR and OR operators would not be attempted unless src_reg
would resolve to a single value, i.e. a known constant value.
This condition is unnecessary, and the following XOR/OR operator
handling could compute a possible better range.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: David Faust <david.faust@oracle.com>
Cc: Jose Marchesi <jose.marchesi@oracle.com>
Cc: Elena Zannoni <elena.zannoni@oracle.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Link: https://lore.kernel.org/r/20240506141849.185293-4-cupertino.miranda@oracle.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent 0922c78f

kernel/bpf/verifier.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -13900,12 +13900,12 @@ static bool is_safe_to_compute_dst_reg_range(struct bpf_insn *insn,
		case BPF_ADD:
		case BPF_SUB:
		case BPF_AND:
		case BPF_XOR:
		case BPF_OR:
		return true;

		/* Compute range for the following only if the src_reg is const.
		*/
		case BPF_XOR:
		case BPF_OR:
		case BPF_MUL:
		return src_is_const;