powerpc/bpf: Fix BPF_MOD when imm == 1

commit 8bbc9d822421d9ac8ff9ed26a3713c9afc69d6c8 upstream.

Only ignore the operation if dividing by 1.

Fixes: 0f3624780b048f ("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>

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 20bfd753bcba6812788ec7d3deb1280bbfd94c11..81e6279c9874fbe25bf2c746d9ef6a61ec27c2b1 100644 (file)
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -408,8 +408,14 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
                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)) {