| Message ID | 20231101-fix-check-stack-write-v2-2-cb7c17b869b0@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | bpf: Fix incorrect immediate spill | expand |
On Wed, 2023-11-01 at 08:33 +0100, Hao Sun wrote: > Add a test to check if the verifier correctly reason about the sign > of an immediate spilled to stack by BPF_ST instruction. > > Signed-off-by: Hao Sun <sunhao.th@gmail.com> > --- > tools/testing/selftests/bpf/verifier/bpf_st_mem.c | 32 +++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c > index 3af2501082b2..0ba23807c46c 100644 > --- a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c > +++ b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c > @@ -65,3 +65,35 @@ > .expected_attach_type = BPF_SK_LOOKUP, > .runs = -1, > }, > +{ > + "BPF_ST_MEM stack imm sign", > + /* Check if verifier correctly reasons about sign of an > + * immediate spilled to stack by BPF_ST instruction. > + * > + * fp[-8] = -44; > + * r0 = fp[-8]; > + * if r0 s< 0 goto ret0; > + * r0 = -1; > + * exit; > + * ret0: > + * r0 = 0; > + * exit; > + */ > + .insns = { > + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, -44), > + BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8), > + BPF_JMP_IMM(BPF_JSLT, BPF_REG_0, 0, 2), > + BPF_MOV64_IMM(BPF_REG_0, -1), > + BPF_EXIT_INSN(), > + BPF_MOV64_IMM(BPF_REG_0, 0), > + BPF_EXIT_INSN(), > + }, > + /* Use prog type that requires return value in range [0, 1] */ > + .prog_type = BPF_PROG_TYPE_SK_LOOKUP, > + .expected_attach_type = BPF_SK_LOOKUP, > + .result = VERBOSE_ACCEPT, > + .runs = -1, > + .errstr = "0: (7a) *(u64 *)(r10 -8) = -44 ; R10=fp0 fp-8_w=-44\ > + 2: (c5) if r0 s< 0x0 goto pc+2\ > + 2: R0_w=-44", > +}, > Please note that this test case fails on CI [0], full log below: 2023-11-01T07:49:51.2841702Z #116/p BPF_ST_MEM stack imm sign FAIL 2023-11-01T07:49:51.2843456Z Unexpected verifier log! 2023-11-01T07:49:51.2844968Z EXP: 2: R0_w=-44 2023-11-01T07:49:51.2845583Z RES: 2023-11-01T07:49:51.2846693Z func#0 @0 2023-11-01T07:49:51.2848932Z 0: R1=ctx(off=0,imm=0) R10=fp0 2023-11-01T07:49:51.2853045Z 0: (7a) *(u64 *)(r10 -8) = -44 ; R10=fp0 fp-8_w=-44 2023-11-01T07:49:51.2857391Z 1: (79) r0 = *(u64 *)(r10 -8) ; R0_w=-44 R10=fp0 fp-8_w=-44 2023-11-01T07:49:51.2859127Z 2: (c5) if r0 s< 0x0 goto pc+2 2023-11-01T07:49:51.2862943Z mark_precise: frame0: last_idx 2 first_idx 0 subseq_idx -1 2023-11-01T07:49:51.2867511Z mark_precise: frame0: regs=r0 stack= before 1: (79) r0 = *(u64 *)(r10 -8) 2023-11-01T07:49:51.2872217Z mark_precise: frame0: regs= stack=-8 before 0: (7a) *(u64 *)(r10 -8) = -44 2023-11-01T07:49:51.2872816Z 5: R0_w=-44 2023-11-01T07:49:51.2875653Z 5: (b7) r0 = 0 ; R0_w=0 2023-11-01T07:49:51.2876493Z 6: (95) exit I suspect that after recent logging fixes instruction number printed after jump changed and that's why test case no longer passes. Note: you can check CI status for submitted patch-sets using link [1]. [0] https://github.com/kernel-patches/bpf/actions/runs/6717053909/job/18254330860 [1] https://patchwork.kernel.org/project/netdevbpf/list/
On Wed, Nov 1, 2023 at 12:05 PM Eduard Zingerman <eddyz87@gmail.com> wrote: > > On Wed, 2023-11-01 at 08:33 +0100, Hao Sun wrote: > > Add a test to check if the verifier correctly reason about the sign > > of an immediate spilled to stack by BPF_ST instruction. > > > > Signed-off-by: Hao Sun <sunhao.th@gmail.com> > > --- > > tools/testing/selftests/bpf/verifier/bpf_st_mem.c | 32 +++++++++++++++++++++++ > > 1 file changed, 32 insertions(+) > > > > diff --git a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c > > index 3af2501082b2..0ba23807c46c 100644 > > --- a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c > > +++ b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c > > @@ -65,3 +65,35 @@ > > .expected_attach_type = BPF_SK_LOOKUP, > > .runs = -1, > > }, > > +{ > > + "BPF_ST_MEM stack imm sign", > > + /* Check if verifier correctly reasons about sign of an > > + * immediate spilled to stack by BPF_ST instruction. > > + * > > + * fp[-8] = -44; > > + * r0 = fp[-8]; > > + * if r0 s< 0 goto ret0; > > + * r0 = -1; > > + * exit; > > + * ret0: > > + * r0 = 0; > > + * exit; > > + */ > > + .insns = { > > + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, -44), > > + BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8), > > + BPF_JMP_IMM(BPF_JSLT, BPF_REG_0, 0, 2), > > + BPF_MOV64_IMM(BPF_REG_0, -1), > > + BPF_EXIT_INSN(), > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > + BPF_EXIT_INSN(), > > + }, > > + /* Use prog type that requires return value in range [0, 1] */ > > + .prog_type = BPF_PROG_TYPE_SK_LOOKUP, > > + .expected_attach_type = BPF_SK_LOOKUP, > > + .result = VERBOSE_ACCEPT, > > + .runs = -1, > > + .errstr = "0: (7a) *(u64 *)(r10 -8) = -44 ; R10=fp0 fp-8_w=-44\ > > + 2: (c5) if r0 s< 0x0 goto pc+2\ > > + 2: R0_w=-44", > > +}, > > > > Please note that this test case fails on CI [0], full log below: > > 2023-11-01T07:49:51.2841702Z #116/p BPF_ST_MEM stack imm sign FAIL > 2023-11-01T07:49:51.2843456Z Unexpected verifier log! > 2023-11-01T07:49:51.2844968Z EXP: 2: R0_w=-44 > 2023-11-01T07:49:51.2845583Z RES: > 2023-11-01T07:49:51.2846693Z func#0 @0 > 2023-11-01T07:49:51.2848932Z 0: R1=ctx(off=0,imm=0) R10=fp0 > 2023-11-01T07:49:51.2853045Z 0: (7a) *(u64 *)(r10 -8) = -44 ; R10=fp0 fp-8_w=-44 > 2023-11-01T07:49:51.2857391Z 1: (79) r0 = *(u64 *)(r10 -8) ; R0_w=-44 R10=fp0 fp-8_w=-44 > 2023-11-01T07:49:51.2859127Z 2: (c5) if r0 s< 0x0 goto pc+2 > 2023-11-01T07:49:51.2862943Z mark_precise: frame0: last_idx 2 first_idx 0 subseq_idx -1 > 2023-11-01T07:49:51.2867511Z mark_precise: frame0: regs=r0 stack= before 1: (79) r0 = *(u64 *)(r10 -8) > 2023-11-01T07:49:51.2872217Z mark_precise: frame0: regs= stack=-8 before 0: (7a) *(u64 *)(r10 -8) = -44 > 2023-11-01T07:49:51.2872816Z 5: R0_w=-44 > 2023-11-01T07:49:51.2875653Z 5: (b7) r0 = 0 ; R0_w=0 > 2023-11-01T07:49:51.2876493Z 6: (95) exit > > I suspect that after recent logging fixes instruction number printed > after jump changed and that's why test case no longer passes. > Yes, so I guess we can just drop the line number there, will send patch v3. > Note: you can check CI status for submitted patch-sets using link [1]. > > [0] https://github.com/kernel-patches/bpf/actions/runs/6717053909/job/18254330860 > [1] https://patchwork.kernel.org/project/netdevbpf/list/ Thanks.
diff --git a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c index 3af2501082b2..0ba23807c46c 100644 --- a/tools/testing/selftests/bpf/verifier/bpf_st_mem.c +++ b/tools/testing/selftests/bpf/verifier/bpf_st_mem.c @@ -65,3 +65,35 @@ .expected_attach_type = BPF_SK_LOOKUP, .runs = -1, }, +{ + "BPF_ST_MEM stack imm sign", + /* Check if verifier correctly reasons about sign of an + * immediate spilled to stack by BPF_ST instruction. + * + * fp[-8] = -44; + * r0 = fp[-8]; + * if r0 s< 0 goto ret0; + * r0 = -1; + * exit; + * ret0: + * r0 = 0; + * exit; + */ + .insns = { + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, -44), + BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8), + BPF_JMP_IMM(BPF_JSLT, BPF_REG_0, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, -1), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + /* Use prog type that requires return value in range [0, 1] */ + .prog_type = BPF_PROG_TYPE_SK_LOOKUP, + .expected_attach_type = BPF_SK_LOOKUP, + .result = VERBOSE_ACCEPT, + .runs = -1, + .errstr = "0: (7a) *(u64 *)(r10 -8) = -44 ; R10=fp0 fp-8_w=-44\ + 2: (c5) if r0 s< 0x0 goto pc+2\ + 2: R0_w=-44", +},
Add a test to check if the verifier correctly reason about the sign of an immediate spilled to stack by BPF_ST instruction. Signed-off-by: Hao Sun <sunhao.th@gmail.com> --- tools/testing/selftests/bpf/verifier/bpf_st_mem.c | 32 +++++++++++++++++++++++ 1 file changed, 32 insertions(+)