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From: Maxim Mikityanskiy <maxtram95@gmail.com>
To: Eduard Zingerman <eddyz87@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>, Mykola Lysenko <mykolal@fb.com>,
	Shuah Khan <shuah@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
	netdev@vger.kernel.org, Maxim Mikityanskiy <maxim@isovalent.com>
Subject: [PATCH bpf-next 05/15] selftests/bpf: Add a test case for 32-bit spill tracking
Date: Wed, 20 Dec 2023 23:40:03 +0200	[thread overview]
Message-ID: <20231220214013.3327288-6-maxtram95@gmail.com> (raw)
In-Reply-To: <20231220214013.3327288-1-maxtram95@gmail.com>

From: Maxim Mikityanskiy <maxim@isovalent.com>

When a range check is performed on a register that was 32-bit spilled to
the stack, the IDs of the two instances of the register are the same, so
the range should also be the same.

Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
---
 .../selftests/bpf/progs/verifier_spill_fill.c | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
index 84eccab36582..f2c1fe5b1dba 100644
--- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
+++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
@@ -737,4 +737,35 @@ __naked void stack_load_preserves_const_precision_subreg(void)
 	: __clobber_common);
 }
 
+SEC("xdp")
+__description("32-bit spilled reg range should be tracked")
+__success __retval(0)
+__naked void spill_32bit_range_track(void)
+{
+	asm volatile("					\
+	call %[bpf_ktime_get_ns];			\
+	/* Make r0 bounded. */				\
+	r0 &= 65535;					\
+	/* Assign an ID to r0. */			\
+	r1 = r0;					\
+	/* 32-bit spill r0 to stack. */			\
+	*(u32*)(r10 - 8) = r0;				\
+	/* Boundary check on r0. */			\
+	if r0 < 1 goto l0_%=;				\
+	/* 32-bit fill r1 from stack. */		\
+	r1 = *(u32*)(r10 - 8);				\
+	/* r1 == r0 => r1 >= 1 always. */		\
+	if r1 >= 1 goto l0_%=;				\
+	/* Dead branch: the verifier should prune it.   \
+	 * Do an invalid memory access if the verifier	\
+	 * follows it.					\
+	 */						\
+	r0 = *(u64*)(r9 + 0);				\
+l0_%=:	r0 = 0;						\
+	exit;						\
+"	:
+	: __imm(bpf_ktime_get_ns)
+	: __clobber_all);
+}
+
 char _license[] SEC("license") = "GPL";
-- 
2.42.1


  parent reply	other threads:[~2023-12-20 21:40 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-20 21:39 [PATCH bpf-next 00/15] Improvements for tracking scalars in the BPF verifier Maxim Mikityanskiy
2023-12-20 21:39 ` [PATCH bpf-next 01/15] selftests/bpf: Fix the u64_offset_to_skb_data test Maxim Mikityanskiy
2023-12-26  9:52   ` Shung-Hsi Yu
2023-12-26 10:38     ` Maxim Mikityanskiy
2023-12-26 13:22       ` Shung-Hsi Yu
2024-01-04  2:22   ` Eduard Zingerman
2023-12-20 21:40 ` [PATCH bpf-next 02/15] bpf: make infinite loop detection in is_state_visited() exact Maxim Mikityanskiy
2023-12-20 21:40 ` [PATCH bpf-next 03/15] selftests/bpf: check if imprecise stack spills confuse infinite loop detection Maxim Mikityanskiy
2023-12-20 21:40 ` [PATCH bpf-next 04/15] bpf: Make bpf_for_each_spilled_reg consider narrow spills Maxim Mikityanskiy
2024-01-04  2:25   ` Eduard Zingerman
2023-12-20 21:40 ` Maxim Mikityanskiy [this message]
2024-01-04  2:25   ` [PATCH bpf-next 05/15] selftests/bpf: Add a test case for 32-bit spill tracking Eduard Zingerman
2023-12-20 21:40 ` [PATCH bpf-next 06/15] bpf: Add the assign_scalar_id_before_mov function Maxim Mikityanskiy
2024-01-04  2:26   ` Eduard Zingerman
2023-12-20 21:40 ` [PATCH bpf-next 07/15] bpf: Add the get_reg_width function Maxim Mikityanskiy
2023-12-20 21:40 ` [PATCH bpf-next 08/15] bpf: Assign ID to scalars on spill Maxim Mikityanskiy
2023-12-25  3:15   ` Alexei Starovoitov
2023-12-25 21:11     ` Maxim Mikityanskiy
2023-12-25 21:26       ` Alexei Starovoitov
2024-01-04  2:26   ` Eduard Zingerman
2023-12-20 21:40 ` [PATCH bpf-next 09/15] selftests/bpf: Test assigning " Maxim Mikityanskiy
2024-01-04  2:26   ` Eduard Zingerman
2023-12-20 21:40 ` [PATCH bpf-next 10/15] bpf: Track spilled unbounded scalars Maxim Mikityanskiy
2024-01-04  2:26   ` Eduard Zingerman
2023-12-20 21:40 ` [PATCH bpf-next 11/15] selftests/bpf: Test tracking " Maxim Mikityanskiy
2024-01-04  2:26   ` Eduard Zingerman
2023-12-20 21:40 ` [PATCH bpf-next 12/15] bpf: Preserve boundaries and track scalars on narrowing fill Maxim Mikityanskiy
2023-12-26  5:29   ` Shung-Hsi Yu
2024-01-04  2:27   ` Eduard Zingerman
2024-01-05 17:48     ` Maxim Mikityanskiy
2023-12-20 21:40 ` [PATCH bpf-next 13/15] selftests/bpf: Add test cases for " Maxim Mikityanskiy
2024-01-04  2:26   ` Eduard Zingerman
2023-12-20 21:40 ` [PATCH bpf-next 14/15] bpf: Optimize state pruning for spilled scalars Maxim Mikityanskiy
2023-12-20 21:40 ` [PATCH bpf-next 15/15] selftests/bpf: states pruning checks for scalar vs STACK_{MISC,ZERO} Maxim Mikityanskiy

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