From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>,
<martin.lau@kernel.org>
Cc: <andrii@kernel.org>, <kernel-team@meta.com>,
Eduard Zingerman <eddyz87@gmail.com>,
Shung-Hsi Yu <shung-hsi.yu@suse.com>
Subject: [PATCH v6 bpf-next 04/17] bpf: derive smin32/smax32 from umin32/umax32 bounds
Date: Wed, 1 Nov 2023 20:37:46 -0700 [thread overview]
Message-ID: <20231102033759.2541186-5-andrii@kernel.org> (raw)
In-Reply-To: <20231102033759.2541186-1-andrii@kernel.org>
All the logic that applies to u64 vs s64, equally applies for u32 vs s32
relationships (just taken in a smaller 32-bit numeric space). So do the
same deduction of smin32/smax32 from umin32/umax32, if we can.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
kernel/bpf/verifier.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8a4cdd2787ec..b93818abe7fc 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2324,6 +2324,13 @@ static void __update_reg_bounds(struct bpf_reg_state *reg)
/* Uses signed min/max values to inform unsigned, and vice-versa */
static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
{
+ /* if u32 range forms a valid s32 range (due to matching sign bit),
+ * try to learn from that
+ */
+ if ((s32)reg->u32_min_value <= (s32)reg->u32_max_value) {
+ reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value);
+ reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value);
+ }
/* Learn sign from signed bounds.
* If we cannot cross the sign boundary, then signed and unsigned bounds
* are the same, so combine. This works even in the negative case, e.g.
--
2.34.1
next prev parent reply other threads:[~2023-11-02 3:38 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-02 3:37 [PATCH v6 bpf-next 00/17] BPF register bounds logic and testing improvements Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 01/17] selftests/bpf: fix RELEASE=1 build for tc_opts Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 02/17] selftests/bpf: satisfy compiler by having explicit return in btf test Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 03/17] bpf: derive smin/smax from umin/max bounds Andrii Nakryiko
2023-11-02 3:37 ` Andrii Nakryiko [this message]
2023-11-02 3:37 ` [PATCH v6 bpf-next 05/17] bpf: derive subreg bounds from full bounds when upper 32 bits are constant Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 06/17] bpf: add special smin32/smax32 derivation from 64-bit bounds Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 07/17] bpf: improve deduction of 64-bit bounds from 32-bit bounds Andrii Nakryiko
2023-11-02 14:39 ` Shung-Hsi Yu
2023-11-02 16:17 ` Andrii Nakryiko
2023-11-03 3:43 ` Shung-Hsi Yu
2023-11-02 3:37 ` [PATCH v6 bpf-next 08/17] bpf: try harder to deduce register bounds from different numeric domains Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 09/17] bpf: drop knowledge-losing __reg_combine_{32,64}_into_{64,32} logic Andrii Nakryiko
2023-11-02 15:14 ` Shung-Hsi Yu
2023-11-02 3:37 ` [PATCH v6 bpf-next 10/17] selftests/bpf: BPF register range bounds tester Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 11/17] bpf: rename is_branch_taken reg arguments to prepare for the second one Andrii Nakryiko
2023-11-02 15:15 ` Shung-Hsi Yu
2023-11-02 3:37 ` [PATCH v6 bpf-next 12/17] bpf: generalize is_branch_taken() to work with two registers Andrii Nakryiko
2023-11-02 15:19 ` Shung-Hsi Yu
2023-11-02 3:37 ` [PATCH v6 bpf-next 13/17] bpf: move is_branch_taken() down Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 14/17] bpf: generalize is_branch_taken to handle all conditional jumps in one place Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 15/17] bpf: unify 32-bit and 64-bit is_branch_taken logic Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 16/17] bpf: prepare reg_set_min_max for second set of registers Andrii Nakryiko
2023-11-02 3:37 ` [PATCH v6 bpf-next 17/17] bpf: generalize reg_set_min_max() to handle two sets of two registers Andrii Nakryiko
2023-11-02 16:10 ` [PATCH v6 bpf-next 00/17] BPF register bounds logic and testing improvements patchwork-bot+netdevbpf
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