[PATCH 4.14 04/25] powerpc/bpf: Fix BPF_MOD when imm == 1

Greg Kroah-Hartman
2021-11-01T09:23:34Z

From: Naveen N. Rao <naveen.n.rao@linux.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@linux.vnet.ibm.com>
Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.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@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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)) {