bpf: fix off-by-one in class whitelisting

We would jump one insn too many, landing in the middle of the subsequent block.

diff --git a/src/core/bpf-devices.c b/src/core/bpf-devices.c
index d83fc44..60cc2f6 100644 (file)
--- a/src/core/bpf-devices.c
+++ b/src/core/bpf-devices.c
@@ -108,7 +108,7 @@ static int bpf_prog_whitelist_class(BPFProgram *prog, int type, const char *acc)
                 return -EINVAL;
 
         const struct bpf_insn insn[] = {
-                BPF_JMP_IMM(BPF_JNE, BPF_REG_2, type, 5), /* compare device type */
+                BPF_JMP_IMM(BPF_JNE, BPF_REG_2, type, 4), /* compare device type */
                 BPF_MOV32_REG(BPF_REG_1, BPF_REG_3), /* calculate access type */
                 BPF_ALU32_IMM(BPF_AND, BPF_REG_1, access),
                 BPF_JMP_REG(BPF_JNE, BPF_REG_1, BPF_REG_3, 1), /* compare access type */