From patchwork Mon Oct 2 19:04:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 13406550 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D8921C688 for ; Mon, 2 Oct 2023 19:04:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65B99C433C9; Mon, 2 Oct 2023 19:04:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696273460; bh=VEsg6fqTYDhVGFa0jJFgmDsU8/UVfT6A/kgPl1u/lKg=; h=Date:From:To:Cc:Subject:From; b=QF68u+gMvrufyxKFrnkBWEMr0/SzIT2kIX44C9Mo0AZB2WHDANcLRhPD3Ge7Whh81 s/argLonEHJVRZu4OnmpvlpQMlad4AHnzvOGTN9YsMF9UAQdYNF1Aa69gyZJ5aGFpA kQ+/DP/j/lSjkIrY2i34ifMUrkMrSxISkfiB1V9dDo7iPzH0mwlKuRn6kYhcf0Yk67 LZWolKmOQbIvzX/wL2//a9Fbe508gumHrFqp1kcf8av3dMjgBLSzpLeWYrtzqdZVp/ a5CNv3ruL7MoM55v+p3K316nThNK2MT2WWTxLuttyS1j0gWsM+tWksFg4asxAdLW6X nbXHL5DhWNykA== Date: Mon, 2 Oct 2023 21:04:15 +0200 From: "Gustavo A. R. Silva" To: Bjorn Helgaas , Logan Gunthorpe Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH v2][next] PCI/P2PDMA: Fix potential undefined behavior bug in struct pci_p2pdma_pagemap Message-ID: Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline `struct dev_pagemap` is a flexible structure, which means that it contains a flexible-array member at the bottom. This could potentially lead to an overwrite of the objects following `pgmap` in `struct pci_p2pdma_pagemap`, when `nr_range > 1`. This is currently not the case (notice that `nr_range` is hardcoded to `1`), however as commit b7b3c01b1915 ("mm/memremap_pages: support multiple ranges per invocation") mentions in the subject line, this code can `support multiple ranges per invocation`. So, we'd better prevent any problems that may arise in the future. Fix this by placing the declaration of object `pgmap` at the end of `struct pci_p2pdma_pagemap`. -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting ready to enable it globally. Reviewed-by: Logan Gunthorpe Signed-off-by: Gustavo A. R. Silva --- Changes in v2: - Remove `Fixes:` tags. (Logan Gunthorpe) - Update changelog text. Make it clear that `nr_range` is hardcoded to `1` (Logan Gunthorpe) - Update subject. - Add Logan's RB. v1: Link: https://lore.kernel.org/linux-hardening/ZRnf6wVOu0IJQ2Ok@work/ drivers/pci/p2pdma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index fa7370f9561a..ab34d3d36a64 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -28,9 +28,9 @@ struct pci_p2pdma { }; struct pci_p2pdma_pagemap { - struct dev_pagemap pgmap; struct pci_dev *provider; u64 bus_offset; + struct dev_pagemap pgmap; }; static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap)