From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Kumar Kartikeya Dwivedi" <memxor@gmail.com>, <bpf@vger.kernel.org>
Cc: "Andrii Nakryiko" <andrii@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Emil Tsalapatis" <emil@etsalapatis.com>,
"Tejun Heo" <tj@kernel.org>, <kkd@meta.com>,
<kernel-team@meta.com>
Subject: Re: [PATCH bpf-next v2 07/18] bpf: Size liveness stack masks by the stack each frame uses
Date: Thu, 24 Sep 2026 15:12:44 +0000 [thread overview]
Message-ID: <DLNN6OBVQG1W.3QKYZXB09YNWO@gmail.com> (raw)
In-Reply-To: <20260924082607.2695649-8-memxor@gmail.com>
On Thu, Sep 24, 2026 at 10:25 AM Kumar Kartikeya Dwivedi <memxor@gmail.com> wrote:
> - at_stack_in = kvmalloc_objs(*at_stack_in, len, GFP_KERNEL_ACCOUNT);
> + at_stack_in = kvmalloc_objs(*at_stack_in, (size_t)len * nslots, GFP_KERNEL_ACCOUNT);
at_stack_in is now len * nslots * sizeof(struct arg_track).
One 8-byte store at fp-2048 makes nslots 256, so the subprog pays
2560 bytes per insn instead of 640.
A subprog with 900K insns and one such store asks kvmalloc for more
than 2G and hits WARN_ON_ONCE(size > INT_MAX) in
__kvmalloc_node_noprof().
Should we clamp it somehow?
next prev parent reply other threads:[~2026-09-24 15:12 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 8:25 [PATCH bpf-next v2 00/18] Raise BPF program stack size to 2KiB Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 01/18] bpf: Add accessors for verifier stack slots Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 02/18] bpf: Widen the stack slot index in the jump history Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 03/18] bpf: Store linked registers in the jump history as an array Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 04/18] bpf: Track backtracking stack slots with bitmaps Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 05/18] bpf: Track scratched stack slots with a bitmap Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 06/18] bpf: Treat unknown-size stack reads as reaching the frame top Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 07/18] bpf: Size liveness stack masks by the stack each frame uses Kumar Kartikeya Dwivedi
2026-09-24 15:12 ` Alexei Starovoitov [this message]
2026-09-24 8:25 ` [PATCH bpf-next v2 08/18] bpf: Grow the verifier id scratch on demand Kumar Kartikeya Dwivedi
2026-09-24 9:13 ` bot+bpf-ci
2026-09-24 9:55 ` Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 09/18] selftests/bpf: Cover the tail call caller stack depth limit Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 10/18] selftests/bpf: Check that narrow stack stores define no slot Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 11/18] selftests/bpf: Check liveness merge of masks with different widths Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 12/18] bpf: Size the per-frame verifier structures for a 2 KiB stack Kumar Kartikeya Dwivedi
2026-09-24 9:13 ` bot+bpf-ci
2026-09-24 9:56 ` Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 13/18] bpf: Bound program stack use by a per-program limit Kumar Kartikeya Dwivedi
2026-09-24 9:13 ` bot+bpf-ci
2026-09-24 9:56 ` Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 14/18] selftests/bpf: Add load conditions on the program stack limit Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 15/18] selftests/bpf: Give the 512-byte stack boundary tests a 2 KiB twin Kumar Kartikeya Dwivedi
2026-09-24 9:13 ` bot+bpf-ci
2026-09-24 9:56 ` Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 16/18] bpf, x86: Allow programs 2 KiB of stack Kumar Kartikeya Dwivedi
2026-09-24 9:13 ` bot+bpf-ci
2026-09-24 9:57 ` Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 17/18] bpf, arm64: " Kumar Kartikeya Dwivedi
2026-09-24 9:00 ` bot+bpf-ci
2026-09-24 9:57 ` Kumar Kartikeya Dwivedi
2026-09-24 8:25 ` [PATCH bpf-next v2 18/18] selftests/bpf: Test the 2 KiB stack budget Kumar Kartikeya Dwivedi
2026-09-24 9:13 ` bot+bpf-ci
2026-09-24 9:58 ` Kumar Kartikeya Dwivedi
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