[PATCH v2 1/3] bfp: fix MOV instruction evaluation

[Konstantin Ananyev]

From: Konstantin Ananyev <konstantin.ananyev at huawei.com>

Verifier might left some register-state values uninitialized while
evaluating MOV instructions.
Add explicit initialization.

Fixes: 8021917293d0 ("bpf: add extra validation for input BPF program")
Cc: stable at dpdk.org

Signed-off-by: Konstantin Ananyev <konstantin.ananyev at huawei.com>
Acked-by: Morten Brørup <mb at smartsharesystems.com>
---
 lib/bpf/bpf_validate.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/bpf/bpf_validate.c b/lib/bpf/bpf_validate.c
index 79be5e917d..11344fff4d 100644
--- a/lib/bpf/bpf_validate.c
+++ b/lib/bpf/bpf_validate.c
@@ -636,14 +636,14 @@ eval_alu(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
 {
 	uint64_t msk;
 	uint32_t op;
-	size_t opsz;
+	size_t opsz, sz;
 	const char *err;
 	struct bpf_eval_state *st;
 	struct bpf_reg_val *rd, rs;
 
-	opsz = (BPF_CLASS(ins->code) == BPF_ALU) ?
+	sz = (BPF_CLASS(ins->code) == BPF_ALU) ?
 		sizeof(uint32_t) : sizeof(uint64_t);
-	opsz = opsz * CHAR_BIT;
+	opsz = sz * CHAR_BIT;
 	msk = RTE_LEN2MASK(opsz, uint64_t);
 
 	st = bvf->evst;
@@ -652,8 +652,10 @@ eval_alu(struct bpf_verifier *bvf, const struct ebpf_insn *ins)
 	if (BPF_SRC(ins->code) == BPF_X) {
 		rs = st->rv[ins->src_reg];
 		eval_apply_mask(&rs, msk);
-	} else
+	} else {
+		rs = (struct bpf_reg_val){.v = {.size = sz,},};
 		eval_fill_imm(&rs, msk, ins->imm);
+	}
 
 	eval_apply_mask(rd, msk);
 
-- 
2.35.3