From ddc665a4bb4b728b4e6ecec8db1b64efa9184b9c Mon Sep 17 00:00:00 2001
From: Daniel Borkmann <daniel@iogearbox.net>
Date: Tue, 2 May 2017 20:34:54 +0200
Subject: [PATCH] bpf, arm64: fix jit branch offset related to ldimm64
When the instruction right before the branch destination is
a 64 bit load immediate, we currently calculate the wrong
jump offset in the ctx->offset[] array as we only account
one instruction slot for the 64 bit load immediate although
it uses two BPF instructions. Fix it up by setting the offset
into the right slot after we incremented the index.
Before (ldimm64 test 1):
[...]
00000020: 52800007 mov w7, #0x0 // #0
00000024: d2800060 mov x0, #0x3 // #3
00000028: d2800041 mov x1, #0x2 // #2
0000002c: eb01001f cmp x0, x1
00000030: 54ffff82 b.cs 0x00000020
00000034: d29fffe7 mov x7, #0xffff // #65535
00000038: f2bfffe7 movk x7, #0xffff, lsl #16
0000003c: f2dfffe7 movk x7, #0xffff, lsl #32
00000040: f2ffffe7 movk x7, #0xffff, lsl #48
00000044: d29dddc7 mov x7, #0xeeee // #61166
00000048: f2bdddc7 movk x7, #0xeeee, lsl #16
0000004c: f2ddddc7 movk x7, #0xeeee, lsl #32
00000050: f2fdddc7 movk x7, #0xeeee, lsl #48
[...]
After (ldimm64 test 1):
[...]
00000020: 52800007 mov w7, #0x0 // #0
00000024: d2800060 mov x0, #0x3 // #3
00000028: d2800041 mov x1, #0x2 // #2
0000002c: eb01001f cmp x0, x1
00000030: 540000a2 b.cs 0x00000044
00000034: d29fffe7 mov x7, #0xffff // #65535
00000038: f2bfffe7 movk x7, #0xffff, lsl #16
0000003c: f2dfffe7 movk x7, #0xffff, lsl #32
00000040: f2ffffe7 movk x7, #0xffff, lsl #48
00000044: d29dddc7 mov x7, #0xeeee // #61166
00000048: f2bdddc7 movk x7, #0xeeee, lsl #16
0000004c: f2ddddc7 movk x7, #0xeeee, lsl #32
00000050: f2fdddc7 movk x7, #0xeeee, lsl #48
[...]
Also, add a couple of test cases to make sure JITs pass
this test. Tested on Cavium ThunderX ARMv8. The added
test cases all pass after the fix.
Fixes: 8eee539ddea0 ("arm64: bpf: fix out-of-bounds read in bpf2a64_offset()")
Reported-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Xi Wang <xi.wang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
arch/arm64/net/bpf_jit_comp.c | 8 +++----
lib/test_bpf.c | 45 +++++++++++++++++++++++++++++++++++
2 files changed, 49 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 4f2b35130f3c4..d68abde52740d 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -776,14 +776,14 @@ static int build_body(struct jit_ctx *ctx)
int ret;
ret = build_insn(insn, ctx);
-
- if (ctx->image == NULL)
- ctx->offset[i] = ctx->idx;
-
if (ret > 0) {
i++;
+ if (ctx->image == NULL)
+ ctx->offset[i] = ctx->idx;
continue;
}
+ if (ctx->image == NULL)
+ ctx->offset[i] = ctx->idx;
if (ret)
return ret;
}
diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 3a7730ca81bee..a0f66280ea502 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -4761,6 +4761,51 @@ static struct bpf_test tests[] = {
{ },
{ { 0, 1 } },
},
+ {
+ /* Mainly testing JIT + imm64 here. */
+ "JMP_JGE_X: ldimm64 test 1",
+ .u.insns_int = {
+ BPF_ALU32_IMM(BPF_MOV, R0, 0),
+ BPF_LD_IMM64(R1, 3),
+ BPF_LD_IMM64(R2, 2),
+ BPF_JMP_REG(BPF_JGE, R1, R2, 2),
+ BPF_LD_IMM64(R0, 0xffffffffffffffffUL),
+ BPF_LD_IMM64(R0, 0xeeeeeeeeeeeeeeeeUL),
+ BPF_EXIT_INSN(),
+ },
+ INTERNAL,
+ { },
+ { { 0, 0xeeeeeeeeU } },
+ },
+ {
+ "JMP_JGE_X: ldimm64 test 2",
+ .u.insns_int = {
+ BPF_ALU32_IMM(BPF_MOV, R0, 0),
+ BPF_LD_IMM64(R1, 3),
+ BPF_LD_IMM64(R2, 2),
+ BPF_JMP_REG(BPF_JGE, R1, R2, 0),
+ BPF_LD_IMM64(R0, 0xffffffffffffffffUL),
+ BPF_EXIT_INSN(),
+ },
+ INTERNAL,
+ { },
+ { { 0, 0xffffffffU } },
+ },
+ {
+ "JMP_JGE_X: ldimm64 test 3",
+ .u.insns_int = {
+ BPF_ALU32_IMM(BPF_MOV, R0, 1),
+ BPF_LD_IMM64(R1, 3),
+ BPF_LD_IMM64(R2, 2),
+ BPF_JMP_REG(BPF_JGE, R1, R2, 4),
+ BPF_LD_IMM64(R0, 0xffffffffffffffffUL),
+ BPF_LD_IMM64(R0, 0xeeeeeeeeeeeeeeeeUL),
+ BPF_EXIT_INSN(),
+ },
+ INTERNAL,
+ { },
+ { { 0, 1 } },
+ },
/* BPF_JMP | BPF_JNE | BPF_X */
{
"JMP_JNE_X: if (3 != 2) return 1",
--
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