linux-kernel - [PATCH 4.14 04/25] powerpc/bpf: Fix BPF

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Date:   Mon,  1 Nov 2021 10:17:16 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Johan Almbladh <johan.almbladh@...finetworks.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Song Liu <songliubraving@...com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Subject: [PATCH 4.14 04/25] powerpc/bpf: Fix BPF_MOD when imm == 1

From: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>

commit 8bbc9d822421d9ac8ff9ed26a3713c9afc69d6c8 upstream.

Only ignore the operation if dividing by 1.

Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
Tested-by: Johan Almbladh <johan.almbladh@...finetworks.com>
Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>
Acked-by: Song Liu <songliubraving@...com>
Acked-by: Johan Almbladh <johan.almbladh@...finetworks.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/c674ca18c3046885602caebb326213731c675d06.1633464148.git.naveen.n.rao@linux.vnet.ibm.com
[cascardo: use PPC_LI instead of EMIT(PPC_RAW_LI)]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/powerpc/net/bpf_jit_comp64.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -426,8 +426,14 @@ static int bpf_jit_build_body(struct bpf
 		case BPF_ALU64 | BPF_DIV | BPF_K: /* dst /= imm */
 			if (imm == 0)
 				return -EINVAL;
-			else if (imm == 1)
-				goto bpf_alu32_trunc;
+			if (imm == 1) {
+				if (BPF_OP(code) == BPF_DIV) {
+					goto bpf_alu32_trunc;
+				} else {
+					PPC_LI(dst_reg, 0);
+					break;
+				}
+			}
 
 			PPC_LI32(b2p[TMP_REG_1], imm);
 			switch (BPF_CLASS(code)) {