netdev - [bpf-next PATCH v2 2/4] bpf: selftests, verifier case for non null pointer check branch taken

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 21 May 2020 13:07:46 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     yhs@...com, andrii.nakryiko@...il.com, ast@...nel.org,
        daniel@...earbox.net
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        john.fastabend@...il.com
Subject: [bpf-next PATCH v2 2/4] bpf: selftests,
 verifier case for non null pointer check branch taken

When we have pointer type that is known to be non-null and comparing
against zero we only follow the non-null branch. This adds tests to
cover this case for reference tracking. Also add the other case when
comparison against a non-zero value and ensure we still fail with
unreleased reference.

Signed-off-by: John Fastabend <john.fastabend@...il.com>
---
 .../testing/selftests/bpf/verifier/ref_tracking.c  |   33 ++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/ref_tracking.c b/tools/testing/selftests/bpf/verifier/ref_tracking.c
index 604b461..056e027 100644
--- a/tools/testing/selftests/bpf/verifier/ref_tracking.c
+++ b/tools/testing/selftests/bpf/verifier/ref_tracking.c
@@ -821,3 +821,36 @@
 	.result = REJECT,
 	.errstr = "invalid mem access",
 },
+{
+	"reference tracking: branch tracking valid pointer null comparison",
+	.insns = {
+	BPF_SK_LOOKUP(sk_lookup_tcp),
+	BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+	BPF_MOV64_IMM(BPF_REG_3, 1),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 0, 1),
+	BPF_MOV64_IMM(BPF_REG_3, 0),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 2),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+	BPF_EMIT_CALL(BPF_FUNC_sk_release),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.result = ACCEPT,
+},
+{
+	"reference tracking: branch tracking valid pointer value comparison",
+	.insns = {
+	BPF_SK_LOOKUP(sk_lookup_tcp),
+	BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+	BPF_MOV64_IMM(BPF_REG_3, 1),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 4),
+	BPF_MOV64_IMM(BPF_REG_3, 0),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 1234, 2),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+	BPF_EMIT_CALL(BPF_FUNC_sk_release),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.errstr = "Unreleased reference",
+	.result = REJECT,
+},