From: Eduard Zingerman <eddyz87@gmail.com>
To: sashiko-reviews@lists.linux.dev
Cc: bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v3 3/5] bpf: infer zext_dst based on static register liveness analysis
Date: Sun, 02 Aug 2026 14:14:35 -0700 [thread overview]
Message-ID: <ddc2fbf63c32eb8b933589d27550f2a8d0eecba0.camel@gmail.com> (raw)
In-Reply-To: <20260802210741.D10C21F000E9@smtp.kernel.org>
On Sun, 2026-08-02 at 21:07 +0000, sashiko-bot@kernel.org wrote:
...
> > @@ -15026,18 +14941,14 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
> > if (insn->imm) {
> > /* off == BPF_ADDR_SPACE_CAST */
> > mark_reg_unknown(env, regs, insn->dst_reg);
> > - if (insn->imm == 1) { /* cast from as(1) to as(0) */
> > + if (insn->imm == 1) /* cast from as(1) to as(0) */
> > dst_reg->type = PTR_TO_ARENA;
> > - /* PTR_TO_ARENA is 32-bit */
> > - dst_reg->subreg_def = env->insn_idx + 1;
> > - }
>
> [Severity: Critical]
> Does this missing zero-extension for BPF_ADDR_SPACE_CAST allow out-of-bounds
> arena access on architectures needing explicit zero-extension?
Nope, in combination with changes to bpf_is_reg64() in the next patch
it does not. bpf_is_reg64() handles BPF_ADDR_SPACE_CAST after that change.
The commit log is not very clear about that, though.
...
next prev parent reply other threads:[~2026-08-02 21:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-02 20:24 [PATCH bpf-next v3 0/5] bpf: infer zext_dst based on static register liveness analysis Eduard Zingerman
2026-08-02 20:24 ` [PATCH bpf-next v3 1/5] bpf: do not print a newline after disassembly in bpf_verbose_insn() Eduard Zingerman
2026-08-03 0:22 ` Quentin Monnet
2026-08-02 20:24 ` [PATCH bpf-next v3 2/5] bpf: track upper 32-bit register halves' liveness in compute_live_registers() Eduard Zingerman
2026-08-02 20:24 ` [PATCH bpf-next v3 3/5] bpf: infer zext_dst based on static register liveness analysis Eduard Zingerman
2026-08-02 21:07 ` sashiko-bot
2026-08-02 21:14 ` Eduard Zingerman [this message]
2026-08-02 20:24 ` [PATCH bpf-next v3 4/5] bpf: simplify the bpf_is_reg64() Eduard Zingerman
2026-08-02 21:26 ` sashiko-bot
2026-08-02 21:40 ` Eduard Zingerman
2026-08-02 20:24 ` [PATCH bpf-next v3 5/5] selftests/bpf: verify zext_dst annotations for various instructions Eduard Zingerman
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