From: Andrey Ignatov <rdna@xxxxxx>
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@xxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
[OP: backport to 4.19]
Signed-off-by: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx>
---
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
