From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f51.google.com (mail-wr1-f51.google.com [209.85.221.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C0F873B3895 for ; Thu, 18 Jun 2026 08:46:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781772377; cv=none; b=m7pboO81VjDnI8Dh+J1a91HOyuzwfJpFhVq399YlINjWpLX+OeKvfQ7DV9ML+pJeZ5zrCDtrGBFXKNR7XStu7SxgciNNEweZJCl+5Xz7Qn2zKlm21M7i0hbGidz26gbOIIBEEJc81/LlWaf7RCrJhm1CMJX6u05oyKve1KO5Suc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781772377; c=relaxed/simple; bh=ZkO6pGqCkfZqy3u/oU51uk/j3lT62505mW0fThy9hk4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WNajTvYoiTd598n8DY2AEE2Hm00tioF0UgOX+O2Eq/QTSHxhvqtuwkBKaP4eMVnCXBkS8mY5bTGrDOc7Xwu2ti+pePgMwvTTpNeEeezAt2Kjl82D6CVs/WhSP2QGsFOOXsmh0n6Fjay6y0zHoI+WYwEJW/gEnpeY6Ikd7b2CkIo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=kPQhdo49; arc=none smtp.client-ip=209.85.221.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kPQhdo49" Received: by mail-wr1-f51.google.com with SMTP id ffacd0b85a97d-463f1165e16so483680f8f.0 for ; Thu, 18 Jun 2026 01:46:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1781772374; x=1782377174; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=3PGCTCQszIeeChHhQclIvtZO9APdlhqX7ENI5kXXs3o=; b=kPQhdo49O+yBje7dRhYtDtHt4mCyMKrFOBAd15Qovc/SviFiJm4TKN+LmQiRyh4JqN hyuCSZBO2MEUlMYVnLqBOOYzjuph6m50697h0zjDRx+qgFZB+HEp1jRfKsB+Gz9poVs9 pzioYQiWuLcIVIHrLu6PqaUu8P3/Vk5ZYlGQOEbPqDFxQdGqV0p/vxClW3OZmZYsDQpW HQ49OyS9Eku0Z92Fot9TDvBC6KAy9skjsFuZx8y+eVHpF7krlHoNuc1kLNUyjVde21cc qXt5wzsKWTaabaEvJUjIR46xsAMvtyFJPHAjzvdq67c/s1EeqzXiucNBaTqFsrjAxU48 9niQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781772374; x=1782377174; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=3PGCTCQszIeeChHhQclIvtZO9APdlhqX7ENI5kXXs3o=; b=Adav9QzXC8d+XRePty826UqOP3En7wtxERTcjWLL3suTrwhCKwtOwjptVmEFcsHZeg wpMaNhjDqr2jQsfM3YlGCLYO7vKH6wvL7Ma6Lq65tYZc8oWFwnRA24dEmaq9ZwIyDqle nBLBEJO02dXIfOwYlPU4wPvl2WvLdQKxII8qxgFlTLHZU3RUnTb/X3jjpZIUF8lmqlQ2 ijfewe3B6TqtkuTMhw+C+9bPB3vhYjT/2VCQ0HT1Jqq7DkSuOTLfPYS8VRGExMSitAkh R1urJB0xbiDH73oxY3EAiLeYafwbPtBCTJCxggOXVZAWkJwr+I+TbZNSy0en7WhTCjBw PMCA== X-Forwarded-Encrypted: i=1; AFNElJ9nE01v4o9OWNJZ/o25WjKoBXqR0MtBGs/G8kq4KAjgohHFz33nLTA390o0lJrFZCLNsLuATm4gAkiDWYs=@vger.kernel.org X-Gm-Message-State: AOJu0YwN+xnjASvZ5Vy20FV04ylD+CRwXi8hOtXBQ8Q6hGwvwKgtScE6 q0z+GBBmrsuQez+pn7doirtmIt/fWKqpWGDdoO3bgy+XpNn2uUPIAwtB X-Gm-Gg: Acq92OFKs65c7CcvMBmcjgRqV0KjJAn1tSYq6IGAEfWdJnuQdEAlrUJsK0DrVjjsmnF h1I+AxprxuThA+lsQAhsZpDIW+wmxCMoPoBNbU0s1WYvyxvLC/qMW3VyZ9X7AcgaIX1bj3kr5aA 0EpcMBdLCju4EXfhh1uGMw+vVFq9Td/Tu43fP4xi9yEfOiiV4qyQQqd/CVyeJQUbWA9boWR4FJJ TSPhD0cIJDf0g9zy2CVR0v2zNKJxUga4BIgs2XZirLv3qHFx3JEjMqbjaWQIwtUwKe+ZgU5wpYn 80ZPKND+a9g/50dVLS8YdfYtAnS5CmIlt4xck3ZduqLaZA9xCeHYVaM4emVhTFOMoG8xHkKK3O3 kCpAFiv2/0nRiGMNWY4UyKsOJuQOT9996i9aWIrVbcasIpcEV2sJUNY37Y4vxkiFuGXMjQA+TBC +dxD5M0IRdjLBC9HfbrxAt1avnJo4BXXaXkZ+d3x5mcaNW8ZdqOR5+1gaNrxfJuZKzGovoV11j/ 0auz3YDNqzoQLwXxDKnTTgLr9uynb8cV6C2ovsogu1qf/ML0yFoGK/w6vFzUL0lHHOMvcyZmbYv VKRmYNM4S29dYbRQ3ZPW5YFFfTXA2clqPVEozwWKKM4= X-Received: by 2002:a05:600c:8189:b0:492:32a0:7f92 with SMTP id 5b1f17b1804b1-492333aabe8mr126392015e9.12.1781772374045; Thu, 18 Jun 2026 01:46:14 -0700 (PDT) Received: from mail.gmail.com (2a01cb0889497e006e99796483dfbc0d.ipv6.abo.wanadoo.fr. [2a01:cb08:8949:7e00:6e99:7964:83df:bc0d]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4922fa96f0esm255435305e9.12.2026.06.18.01.46.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jun 2026 01:46:13 -0700 (PDT) Date: Thu, 18 Jun 2026 10:46:11 +0200 From: Paul Chaignon To: Sun Jian Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, memxor@gmail.com, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, shuah@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, toke@redhat.com, lorenzo@kernel.org Subject: Re: [PATCH bpf v3 1/2] bpf: Fix partial copy of non-linear test_run output Message-ID: References: <20260617093557.63880-1-sun.jian.kdev@gmail.com> <20260617093557.63880-2-sun.jian.kdev@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260617093557.63880-2-sun.jian.kdev@gmail.com> On Wed, Jun 17, 2026 at 05:35:56PM +0800, Sun Jian wrote: > For non-linear test_run output, bpf_test_finish() derives the linear > data copy length from copy_size - frag_size. This only matches the > linear data length when copy_size is the full packet size. > > When userspace provides a short data_out buffer, copy_size is clamped to > that buffer size. If copy_size is smaller than frag_size, the computed > length becomes negative and bpf_test_finish() returns -ENOSPC before > copying the packet prefix or updating data_size_out. > > Compute the linear data length from the packet layout instead, and clamp > the linear copy length to copy_size. This preserves the expected > partial-copy semantics: return -ENOSPC, copy the packet prefix that fits > in data_out, and report the full packet length through data_size_out. > > Fixes: 7855e0db150ad ("bpf: test_run: add xdp_shared_info pointer in bpf_test_finish signature") > Signed-off-by: Sun Jian > --- > net/bpf/test_run.c | 8 ++------ > 1 file changed, 2 insertions(+), 6 deletions(-) > > diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c > index 2bc04feadfab..f15c613aaa4e 100644 > --- a/net/bpf/test_run.c > +++ b/net/bpf/test_run.c > @@ -453,12 +453,8 @@ static int bpf_test_finish(const union bpf_attr *kattr, > } > > if (data_out) { > - int len = sinfo ? copy_size - frag_size : copy_size; > - > - if (len < 0) { > - err = -ENOSPC; > - goto out; > - } > + u32 head_len = size - frag_size; > + u32 len = min(copy_size, head_len); > > if (copy_to_user(data_out, data, len)) > goto out; Acked-by: Paul Chaignon