From: Eduard Zingerman <eddyz87@gmail.com>
To: Maxim Mikityanskiy <maxtram95@gmail.com>
Cc: bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next 10/15] bpf: Track spilled unbounded scalars
Date: Thu, 04 Jan 2024 04:26:37 +0200 [thread overview]
Message-ID: <6e363e41b6780a7515840df26eeca95f0f3ea388.camel@gmail.com> (raw)
In-Reply-To: <20231220214013.3327288-11-maxtram95@gmail.com>
On Wed, 2023-12-20 at 23:40 +0200, Maxim Mikityanskiy wrote:
> > From: Maxim Mikityanskiy <maxim@isovalent.com>
> >
> > Support the pattern where an unbounded scalar is spilled to the stack,
> > then boundary checks are performed on the src register, after which the
> > stack frame slot is refilled into a register.
> >
> > Before this commit, the verifier didn't treat the src register and the
> > stack slot as related if the src register was an unbounded scalar. The
> > register state wasn't copied, the id wasn't preserved, and the stack
> > slot was marked as STACK_MISC. Subsequent boundary checks on the src
> > register wouldn't result in updating the boundaries of the spilled
> > variable on the stack.
> >
> > After this commit, the verifier will preserve the bond between src and
> > dst even if src is unbounded, which permits to do boundary checks on src
> > and refill dst later, still remembering its boundaries. Such a pattern
> > is sometimes generated by clang when compiling complex long functions.
> >
> > One test is adjusted to reflect the fact that an untracked register is
> > marked as precise at an earlier stage, and one more test is adjusted to
> > reflect that now unbounded scalars are tracked.
> >
> > Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
> > ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
next prev parent reply other threads:[~2024-01-04 2:26 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 ` [PATCH bpf-next 05/15] selftests/bpf: Add a test case for 32-bit spill tracking Maxim Mikityanskiy
2024-01-04 2:25 ` 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 [this message]
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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