linux-kernel - [PATCH 5.4 49/83] bpf, x86_32: Fix logic error in BPF

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Date:   Fri,  1 May 2020 15:23:28 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Wang YanQing <udknight@...il.com>,
        Alexei Starovoitov <ast@...nel.org>
Subject: [PATCH 5.4 49/83] bpf, x86_32: Fix logic error in BPF_LDX zero-extension

From: Wang YanQing <udknight@...il.com>

commit 5ca1ca01fae1e90f8d010eb1d83374f28dc11ee6 upstream.

When verifier_zext is true, we don't need to emit code
for zero-extension.

Fixes: 836256bf5f37 ("x32: bpf: eliminate zero extension code-gen")
Signed-off-by: Wang YanQing <udknight@...il.com>
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Link: https://lore.kernel.org/bpf/20200423050637.GA4029@udknight
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/net/bpf_jit_comp32.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/net/bpf_jit_comp32.c
+++ b/arch/x86/net/bpf_jit_comp32.c
@@ -1847,7 +1847,7 @@ static int do_jit(struct bpf_prog *bpf_p
 			case BPF_B:
 			case BPF_H:
 			case BPF_W:
-				if (!bpf_prog->aux->verifier_zext)
+				if (bpf_prog->aux->verifier_zext)
 					break;
 				if (dstk) {
 					EMIT3(0xC7, add_1reg(0x40, IA32_EBP),