x86: bpf_jit: fix FROM_BE16 and FROM_LE16/32 instructions

FROM_BE16:
'ror %reg, 8' doesn't clear upper bits of the register,
so use additional 'movzwl' insn to zero extend 16 bits into 64

FROM_LE16:
should zero extend lower 16 bits into 64 bit

FROM_LE32:
should zero extend lower 32 bits into 64 bit

Fixes: 89aa075832b0 ("net: sock: allow eBPF programs to be attached to sockets")
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 987514396c1e443376bffe70e050b72f86509102..99f76103c6b733e3d587652e3ab4228d20d57ac9 100644 (file)
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -559,6 +559,13 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
                                if (is_ereg(dst_reg))
                                        EMIT1(0x41);
                                EMIT3(0xC1, add_1reg(0xC8, dst_reg), 8);
+
+                               /* emit 'movzwl eax, ax' */
+                               if (is_ereg(dst_reg))
+                                       EMIT3(0x45, 0x0F, 0xB7);
+                               else
+                                       EMIT2(0x0F, 0xB7);
+                               EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
                                break;
                        case 32:
                                /* emit 'bswap eax' to swap lower 4 bytes */
@@ -577,6 +584,27 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
                        break;
 
                case BPF_ALU | BPF_END | BPF_FROM_LE:
+                       switch (imm32) {
+                       case 16:
+                               /* emit 'movzwl eax, ax' to zero extend 16-bit
+                                * into 64 bit
+                                */
+                               if (is_ereg(dst_reg))
+                                       EMIT3(0x45, 0x0F, 0xB7);
+                               else
+                                       EMIT2(0x0F, 0xB7);
+                               EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
+                               break;
+                       case 32:
+                               /* emit 'mov eax, eax' to clear upper 32-bits */
+                               if (is_ereg(dst_reg))
+                                       EMIT1(0x45);
+                               EMIT2(0x89, add_2reg(0xC0, dst_reg, dst_reg));
+                               break;
+                       case 64:
+                               /* nop */
+                               break;
+                       }
                        break;
 
                        /* ST: *(u8*)(dst_reg + off) = imm */