netdev - [PATCH net-next 2/8] bpf: don't check spilled reg state for non-STACK

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Date:   Sun, 11 Jun 2017 00:50:41 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     davem@...emloft.net
Cc:     ast@...com, netdev@...r.kernel.org,
        Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH net-next 2/8] bpf: don't check spilled reg state for non-STACK_SPILLed type slots

spilled_regs[] state is only used for stack slots of type STACK_SPILL,
never for STACK_MISC. Right now, in states_equal(), even if we have
old and current stack state of type STACK_MISC, we compare spilled_regs[]
for that particular offset. Just skip these like we do everywhere else.

Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Alexei Starovoitov <ast@...nel.org>
---
 kernel/bpf/verifier.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 14ccb07..d031b3b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2828,6 +2828,8 @@ static bool states_equal(struct bpf_verifier_env *env,
 			return false;
 		if (i % BPF_REG_SIZE)
 			continue;
+		if (old->stack_slot_type[i] != STACK_SPILL)
+			continue;
 		if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE],
 			   &cur->spilled_regs[i / BPF_REG_SIZE],
 			   sizeof(old->spilled_regs[0])))
-- 
1.9.3