linux-kernel - [PATCH 4.14 28/47] bpf: Move off_reg into sanitize_ptr

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Date:   Tue,  8 Jun 2021 20:27:11 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Frank van der Linden <fllinden@...zon.com>
Subject: [PATCH 4.14 28/47] bpf: Move off_reg into sanitize_ptr_alu

From: Daniel Borkmann <daniel@...earbox.net>

commit 6f55b2f2a1178856c19bbce2f71449926e731914 upstream.

Small refactor to drag off_reg into sanitize_ptr_alu(), so we later on can
use off_reg for generalizing some of the checks for all pointer types.

Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Reviewed-by: John Fastabend <john.fastabend@...il.com>
Acked-by: Alexei Starovoitov <ast@...nel.org>
[fllinden@...zon.com: fix minor contextual conflict for 4.14]
Signed-off-by: Frank van der Linden <fllinden@...zon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 kernel/bpf/verifier.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2094,11 +2094,12 @@ static int sanitize_val_alu(struct bpf_v
 static int sanitize_ptr_alu(struct bpf_verifier_env *env,
 			    struct bpf_insn *insn,
 			    const struct bpf_reg_state *ptr_reg,
-			    struct bpf_reg_state *dst_reg,
-			    bool off_is_neg)
+			    const struct bpf_reg_state *off_reg,
+			    struct bpf_reg_state *dst_reg)
 {
 	struct bpf_verifier_state *vstate = env->cur_state;
 	struct bpf_insn_aux_data *aux = cur_aux(env);
+	bool off_is_neg = off_reg->smin_value < 0;
 	bool ptr_is_dst_reg = ptr_reg == dst_reg;
 	u8 opcode = BPF_OP(insn->code);
 	u32 alu_state, alu_limit;
@@ -2224,7 +2225,7 @@ static int adjust_ptr_min_max_vals(struc
 
 	switch (opcode) {
 	case BPF_ADD:
-		ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
+		ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg);
 		if (ret < 0) {
 			verbose("R%d tried to add from different maps, paths, or prohibited types\n", dst);
 			return ret;
@@ -2279,7 +2280,7 @@ static int adjust_ptr_min_max_vals(struc
 		}
 		break;
 	case BPF_SUB:
-		ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
+		ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg);
 		if (ret < 0) {
 			verbose("R%d tried to sub from different maps, paths, or prohibited types\n", dst);
 			return ret;