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>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bdaf0413bf06f3515cb92912dc5a774a8604faf3..1f6deb3e44c5093801a2f08f2f9d14aba73ac08b 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -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;