2 files changed, 29 insertions, 2 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 66bec36ec1ec..47dcd3aa6e23 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1637,6 +1637,8 @@ static int do_check(struct verifier_env *env)
                         if (err)
                                 return err;
 
+                        src_reg_type = regs[insn->src_reg].type;
+
                         /* check that memory (src_reg + off) is readable,
                          * the state of dst_reg will be updated by this func
                          */
@@ -1646,9 +1648,12 @@ static int do_check(struct verifier_env *env)
                         if (err)
                                 return err;
 
-                        src_reg_type = regs[insn->src_reg].type;
+                        if (BPF_SIZE(insn->code) != BPF_W) {
+                                insn_idx++;
+                                continue;
+                        }
 
-                        if (insn->imm == 0 && BPF_SIZE(insn->code) == BPF_W) {
+                        if (insn->imm == 0) {
                                 /* saw a valid insn
                                  * dst_reg = *(u32 *)(src_reg + off)
                                  * use reserved 'imm' field to mark this insn
diff --git a/samples/bpf/test_verifier.c b/samples/bpf/test_verifier.c
index 9ab645698ffb..12f3780af73f 100644
--- a/samples/bpf/test_verifier.c
+++ b/samples/bpf/test_verifier.c
@@ -721,6 +721,28 @@ static struct bpf_test tests[] = {
                 .errstr = "different pointers",
                 .result = REJECT,
         },
+        {
+                "access skb fields bad4",
+                .insns = {
+                        BPF_JMP_IMM(BPF_JGE, BPF_REG_1, 0, 3),
+                        BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1,
+                                    offsetof(struct __sk_buff, len)),
+                        BPF_MOV64_IMM(BPF_REG_0, 0),
+                        BPF_EXIT_INSN(),
+                        BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+                        BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+                        BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+                        BPF_LD_MAP_FD(BPF_REG_1, 0),
+                        BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+                        BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+                        BPF_EXIT_INSN(),
+                        BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+                        BPF_JMP_IMM(BPF_JA, 0, 0, -13),
+                },
+                .fixup = {7},
+                .errstr = "different pointers",
+                .result = REJECT,
+        },
 };
 
 static int probe_filter_length(struct bpf_insn *fp)