linux-kernel - [PATCH 4.4 05/73] bpf/verifier: reject invalid LD_ABS

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Message-Id: <20160517011452.138652627@linuxfoundation.org>
Date:	Mon, 16 May 2016 18:14:35 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 05/73] bpf/verifier: reject invalid LD_ABS | BPF_DW instruction

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexei Starovoitov <ast@...com>

[ Upstream commit d82bccc69041a51f7b7b9b4a36db0772f4cdba21 ]

verifier must check for reserved size bits in instruction opcode and
reject BPF_LD | BPF_ABS | BPF_DW and BPF_LD | BPF_IND | BPF_DW instructions,
otherwise interpreter will WARN_RATELIMIT on them during execution.

Fixes: ddd872bc3098 ("bpf: verifier: add checks for BPF_ABS | BPF_IND instructions")
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Acked-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 kernel/bpf/verifier.c |    1 +
 1 file changed, 1 insertion(+)

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1348,6 +1348,7 @@ static int check_ld_abs(struct verifier_
 	}
 
 	if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
+	    BPF_SIZE(insn->code) == BPF_DW ||
 	    (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
 		verbose("BPF_LD_ABS uses reserved fields\n");
 		return -EINVAL;