From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f174.google.com (mail-qk1-f174.google.com [209.85.222.174]) (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 0C1CF3BED46 for ; Tue, 19 May 2026 21:07:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779224870; cv=none; b=kH7ZPauhraNGt4kMaiqQSTwOfm5MLnMO2Efj01nOltlzwqHe9SbM43pxP76F2zh9QcLxugeCk1iv7WDC8btWEYOosJY2Ujmn4YijXVL8FfAHXCAd4rJAAFVKPI8vo5IzX1e73zypu1fcbTy3m1JEiKeJheK0dGHr4ZELa6riZgc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779224870; c=relaxed/simple; bh=8Da4dPOOKKC9Yw0fFkeVaJMYMU3MEjd7WJQsKu8y03k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JzoXmO6yEtHyWQdQEGPFWdVEy34OTp6QgGbpjlwhsenYjMTxwlHFHI2namNSZvcoQVH7DGSsulqcPe52d4Xz34brX3EkuYoE5Hz15VzGpE3x9gQURBrz9Lukvw4bZQCKaPU53/Ku4RtSUlJsTFezda7MMQ0llio8/xXpGKrI9QM= 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=Lvk7k1J0; arc=none smtp.client-ip=209.85.222.174 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="Lvk7k1J0" Received: by mail-qk1-f174.google.com with SMTP id af79cd13be357-902deb2412fso520362785a.3 for ; Tue, 19 May 2026 14:07:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779224868; x=1779829668; 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=QeekahOvLmAA/dYAwVekuXUChV8CZojKF427f4ixlQQ=; b=Lvk7k1J0rAwHXxw50LFHzA6K3iRoNoQbSO63eMTs3w7slIRoI4LfahfOZfN4mKDscU 1ol2gL/5rIpQQ4yY86iO6/qGgOPVmqe77niTPaJatpfN7nZ77MQQU6uFzA2b8TS7MW2o oBu8+5zN5rN4WbV6zkM/k1pUoKa1FO3Bcpls5W71P1eAVajepPZdg4ix8dPD5c2jzLB6 meFdGbM5Yf8crnXKpxMdCXdHLlOATZhMRTPP2OvZ/RC6wSmiPjEpJjPjcoYpqfBSpLy7 0UCP/iwzMP/3m7BuWbxmAQgLdR4Q+9wDUj/ZzPDnhu6v00dCv8sjs/I2OQ5KNI/LhGMG TM0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779224868; x=1779829668; 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=QeekahOvLmAA/dYAwVekuXUChV8CZojKF427f4ixlQQ=; b=sLEMljSo4g5Kc7heJOQlsFysUcqQ+fvxg6H3M/HIffpyLgQHcb3N3WEfsBwbGSf+R0 TIZkkjr0czoXJOSp8WgF9wJD3azUNnntw6KeizSJPcGzThsQwOEIsuxrJ050t8gajN7w cM1AIaMtXtvhdrrlZTggDAXr8qu/FCvWPcEXE3xtht7Wh8KSODBxIhPY/M6NUIQOJ7AQ bba2A6f1sr0/Ggj7lPPQIMcoCj5IDofwM2i5+SuQr7d56Lnrqwv7+s/6czREW5d8CXN2 F0e4jarHpSjIA9sqDqEfTrkj024pGbRZ7pwfz6jGrIumcRTbahWoYWQqUYet5G+7Fy/s RBZQ== X-Forwarded-Encrypted: i=1; AFNElJ/5A88uTfkYZ/dk4H7h3SB/ABdV2VRgeXhQCnhZunBU7moU6OdSX6RDwtD2MdDCTTKdp5ZLLdoXsUcOmXY=@vger.kernel.org X-Gm-Message-State: AOJu0YzvisxnP6Jenb1MV1qODdmkYA6MEdYx3pkLaRb7oHS7XlWjgusr 4SvPZK6iOtYuUqHpDFWR4jIf4NbbdZjAMnfX8vDCaXg0TKsz0Mqlwb4s X-Gm-Gg: Acq92OHCHNQv8YMhLTSWT1Ufind1sN6zVPghQOsElqx4UIZz2BL02vmtWl72DOR6nOg AVy4aUewgsoBhRr1kAc3AdfR3oAPA7aniaCCek6HNtOEPZV76pORYhO8Q1kXR7xm0EqGilixCUK ns931zMplmm/gP7GpW3nLDhOL0U+euYBK3fUwm6rtMkubU2E3BdMCvcCmCLNBrDcdJedyAbJdci 5uA3HNXG5yEBIPe3F9XBd5eEb0Q83aVYBOU393ku9sUFBdAw1EL/IaN39wyXghgv7VgdCzME2h0 nqUOjgPZd2ram0TuBXMdb66XYpW4vvxLgAShqkeIiLNebbFJffmBpogMjaw3khzM6Qh/3qpMIKj kiD+atx+oQllHiLdqgR+XwOi/svgXByprr8sYr+KKH6nYoIHxV4aVw3cjFuTckcWokP8hX4gK6y 2k/g9mWIA6CwxXytn2vJvGaFL6PZefjsDZAQ58QkyByF9HBvglP1oehqXG8Q== X-Received: by 2002:a05:620a:294f:b0:8eb:41de:fb43 with SMTP id af79cd13be357-911cca9b97amr3243513785a.10.1779224867891; Tue, 19 May 2026 14:07:47 -0700 (PDT) Received: from devvm29614.prn0.facebook.com ([2a03:2880:f814:1e::]) by smtp.gmail.com with ESMTPSA id af79cd13be357-910bc83bbf5sm1964749085a.28.2026.05.19.14.07.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 May 2026 14:07:47 -0700 (PDT) Date: Tue, 19 May 2026 14:07:43 -0700 From: Bobby Eshleman To: David Carlier Cc: netdev@vger.kernel.org, stable@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, sdf@fomichev.me, sdf.kernel@gmail.com, kaiyuanz@google.com, almasrymina@google.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH net v2] net: devmem: reject dma-buf bind with non-page-aligned size or SG length Message-ID: References: <20260519203530.66310-1-devnexen@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: <20260519203530.66310-1-devnexen@gmail.com> On Tue, May 19, 2026 at 09:35:30PM +0100, David Carlier wrote: > net_devmem_bind_dmabuf() trusts dmabuf->size and sg_dma_len() to be > PAGE_SIZE multiples without checking: > > - tx_vec is sized dmabuf->size / PAGE_SIZE, and > net_devmem_get_niov_at() only bounds-checks virt_addr < dmabuf->size > before indexing tx_vec[virt_addr / PAGE_SIZE]. With size = > N*PAGE_SIZE + r (1 <= r < PAGE_SIZE), sendmsg() at iov_base = > N*PAGE_SIZE passes the bound check and reads tx_vec[N] -- one past. > > - owner->area.num_niovs = len / PAGE_SIZE while gen_pool_add_owner() > covers the full byte len, so a non-page-multiple non-final sg > desyncs num_niovs from the gen_pool region for every later sg, on > both RX and TX. > > dma-buf does not require page-aligned sizes, so the bind path has to > enforce what its own indexing assumes. Reject both with -EINVAL. > > The size check is TX-only (only tx_vec is sized off dmabuf->size); the > SG-length check covers both directions. > > Fixes: bd61848900bf ("net: devmem: Implement TX path") > Cc: stable@vger.kernel.org > Signed-off-by: David Carlier > --- > Changes in v2: > - Reframe commit message around the kernel-side OOB instead of > "real exporters already page-align", which read as the OOB being > unreachable and undercut Cc: stable (Stanislav Fomichev). > - Hoist the SG-length check out of the if (TX) branch so it covers > RX too; RX has the same num_niovs / gen_pool desync on a > contract-violating exporter, just without an OOB. Keep the > size-multiple check TX-only (Stanislav Fomichev). > - Drop bool todevice; compare direction == DMA_TO_DEVICE inline to > match the existing call site at the tx_vec[] assignment > (Bobby Eshleman). > > net/core/devmem.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/net/core/devmem.c b/net/core/devmem.c > index 468344739db2..4f71de44c0fb 100644 > --- a/net/core/devmem.c > +++ b/net/core/devmem.c > @@ -241,6 +241,11 @@ net_devmem_bind_dmabuf(struct net_device *dev, > } > > if (direction == DMA_TO_DEVICE) { > + if (!IS_ALIGNED(dmabuf->size, PAGE_SIZE)) { > + err = -EINVAL; > + NL_SET_ERR_MSG(extack, "TX dma-buf size must be a multiple of PAGE_SIZE"); > + goto err_unmap; > + } > binding->tx_vec = kvmalloc_objs(struct net_iov *, > dmabuf->size / PAGE_SIZE); > if (!binding->tx_vec) { > @@ -267,6 +272,12 @@ net_devmem_bind_dmabuf(struct net_device *dev, > size_t len = sg_dma_len(sg); > struct net_iov *niov; > > + if (!IS_ALIGNED(len, PAGE_SIZE)) { > + err = -EINVAL; > + NL_SET_ERR_MSG(extack, "dma-buf SG length must be PAGE_SIZE aligned"); > + goto err_free_chunks; > + } > + > owner = kzalloc_node(sizeof(*owner), GFP_KERNEL, > dev_to_node(&dev->dev)); > if (!owner) { > -- > 2.53.0 LGTM. Reviewed-by: Bobby Eshleman