From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Eduard Zingerman" <eddyz87@gmail.com>, <bpf@vger.kernel.org>,
<andrii@kernel.org>
Cc: <daniel@iogearbox.net>, <kernel-team@fb.com>,
<yonghong.song@linux.dev>, <memxor@gmail.com>
Subject: Re: [PATCH bpf-next v2 1/2] bpf: reject pointer operands for 32-bit recurrences/latches
Date: Wed, 21 Oct 2026 22:22:13 +0000 [thread overview]
Message-ID: <DMAV87WUFF7M.1PU3M3CCZJDQJ@gmail.com> (raw)
In-Reply-To: <20261021185609.607075-1-eddyz87@gmail.com>
On Wed, Oct 21, 2026 at 11:56 AM Eduard Zingerman <eddyz87@gmail.com> wrote:
> Fixes: df4761bd441c ("bpf: Support 32-bit linear scalar evolution")
sorry, few commits were dropped from bpf-next.
It's 32e962577d2d now.
> + /* 32-bit ALU operations on pointers convert them to scalars */
> + if (coefs.zext32 && reg->type != SCALAR_VALUE)
> + goto cant_widen;
le64 does the same without zext32.
r7 = map_value, r1 = 0
l: r7 = le64 r7
if r7 < 100 goto out
if r7 > 1000 goto out
r7 += 8
r1 += 1
if r1 != 4 goto l
On little endian transfer() treats le64 as a nop, so r7 at the header
is (linear r7 8), while check_alu_op() makes it an unknown scalar.
At the backedge r7 is a scalar 108..1008 and bpf_clamp_scev_regs()
intersects it with 0..24, the offsets of map_value at the loop entry:
verifier bug: scev clamp produced empty range for r7
Should bpf_clamp_scev_regs() skip the reg when
entry_reg->type != reg->type
?
next prev parent reply other threads:[~2026-10-21 22:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-21 18:56 [PATCH bpf-next v2 1/2] bpf: reject pointer operands for 32-bit recurrences/latches Eduard Zingerman
2026-10-21 18:56 ` [PATCH bpf-next v2 2/2] selftests/bpf: " Eduard Zingerman
2026-10-21 18:57 ` [PATCH bpf-next v2 1/2] bpf: reject " Eduard Zingerman
2026-10-21 22:22 ` Alexei Starovoitov [this message]
2026-10-21 22:50 ` Eduard Zingerman
2026-10-23 1:04 ` Eduard Zingerman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=DMAV87WUFF7M.1PU3M3CCZJDQJ@gmail.com \
--to=alexei.starovoitov@gmail.com \
--cc=andrii@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=kernel-team@fb.com \
--cc=memxor@gmail.com \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox