From: Ovidiu Panait <ovidiu.panait@windriver.com>
To: stable@vger.kernel.org
Cc: bpf@vger.kernel.org, daniel@iogearbox.net
Subject: [PATCH 4.19 07/13] selftests/bpf: Test variable offset stack access
Date: Mon, 13 Sep 2021 18:35:31 +0300 [thread overview]
Message-ID: <20210913153537.2162465-8-ovidiu.panait@windriver.com> (raw)
In-Reply-To: <20210913153537.2162465-1-ovidiu.panait@windriver.com>
From: Andrey Ignatov <rdna@fb.com>
commit 8ff80e96e3ccea5ff0a890d4f18997e0344dbec2 upstream.
Test different scenarios of indirect variable-offset stack access: out of
bound access (>0), min_off below initialized part of the stack,
max_off+size above initialized part of the stack, initialized stack.
Example of output:
...
#856/p indirect variable-offset stack access, out of bound OK
#857/p indirect variable-offset stack access, max_off+size > max_initialized OK
#858/p indirect variable-offset stack access, min_off < min_initialized OK
#859/p indirect variable-offset stack access, ok OK
...
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
[OP: backport to 4.19]
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
---
tools/testing/selftests/bpf/test_verifier.c | 79 ++++++++++++++++++++-
1 file changed, 77 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 6b9ed915c6b0..1ded69b9fd77 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -8495,7 +8495,7 @@ static struct bpf_test tests[] = {
.prog_type = BPF_PROG_TYPE_LWT_IN,
},
{
- "indirect variable-offset stack access",
+ "indirect variable-offset stack access, out of bound",
.insns = {
/* Fill the top 8 bytes of the stack */
BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
@@ -8516,10 +8516,85 @@ static struct bpf_test tests[] = {
BPF_EXIT_INSN(),
},
.fixup_map1 = { 5 },
- .errstr = "variable stack read R2",
+ .errstr = "invalid stack type R2 var_off",
.result = REJECT,
.prog_type = BPF_PROG_TYPE_LWT_IN,
},
+ {
+ "indirect variable-offset stack access, max_off+size > max_initialized",
+ .insns = {
+ /* Fill only the second from top 8 bytes of the stack. */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0),
+ /* Get an unknown value. */
+ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+ /* Make it small and 4-byte aligned. */
+ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4),
+ BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16),
+ /* Add it to fp. We now have either fp-12 or fp-16, but we don't know
+ * which. fp-12 size 8 is partially uninitialized stack.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Dereference it indirectly. */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map1 = { 5 },
+ .errstr = "invalid indirect read from stack var_off",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+ },
+ {
+ "indirect variable-offset stack access, min_off < min_initialized",
+ .insns = {
+ /* Fill only the top 8 bytes of the stack. */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ /* Get an unknown value */
+ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+ /* Make it small and 4-byte aligned. */
+ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4),
+ BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16),
+ /* Add it to fp. We now have either fp-12 or fp-16, but we don't know
+ * which. fp-16 size 8 is partially uninitialized stack.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Dereference it indirectly. */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map1 = { 5 },
+ .errstr = "invalid indirect read from stack var_off",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+ },
+ {
+ "indirect variable-offset stack access, ok",
+ .insns = {
+ /* Fill the top 16 bytes of the stack. */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0),
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ /* Get an unknown value. */
+ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+ /* Make it small and 4-byte aligned. */
+ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4),
+ BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16),
+ /* Add it to fp. We now have either fp-12 or fp-16, we don't know
+ * which, but either way it points to initialized stack.
+ */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+ /* Dereference it indirectly. */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map1 = { 6 },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_LWT_IN,
+ },
{
"direct stack access with 32-bit wraparound. test1",
.insns = {
--
2.25.1
next prev parent reply other threads:[~2021-09-13 15:36 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 15:35 [PATCH 4.19 00/13] bpf: backport fixes for CVE-2021-34556/CVE-2021-35477 Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 01/13] bpf/verifier: per-register parent pointers Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 02/13] bpf: correct slot_type marking logic to allow more stack slot sharing Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 03/13] bpf: Support variable offset stack access from helpers Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 04/13] bpf: Reject indirect var_off stack access in raw mode Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 05/13] bpf: Reject indirect var_off stack access in unpriv mode Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 06/13] bpf: Sanity check max value for var_off stack access Ovidiu Panait
2021-09-13 15:35 ` Ovidiu Panait [this message]
2021-09-13 15:35 ` [PATCH 4.19 08/13] bpf: track spill/fill of constants Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 09/13] selftests/bpf: fix tests due to const spill/fill Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 10/13] bpf: Introduce BPF nospec instruction for mitigating Spectre v4 Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 11/13] bpf: Fix leakage due to insufficient speculative store bypass mitigation Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 12/13] bpf: verifier: Allocate idmap scratch in verifier env Ovidiu Panait
2021-09-13 15:35 ` [PATCH 4.19 13/13] bpf: Fix pointer arithmetic mask tightening under state pruning Ovidiu Panait
2021-09-15 12:39 ` [PATCH 4.19 00/13] bpf: backport fixes for CVE-2021-34556/CVE-2021-35477 Greg KH
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