From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794327015; b=s4P8OlLlTIy6iIqhDo1dK6HdI9q42vmUVkCOBeZqo0qawiKOIKNnW4IQgDty22os0Hcn sJDA0Bg6mxMf1AwK33o6AThpjzZmpkYSNzJFiT0zGp8PhBywjBb5W6esakBdXmrIFZqe+ vL9iLj8sOBjYpjtghl+JRNYb5tKTo8rZy9WC415JNVyaUy8Vo+zAD0gwjohly9bDSaM1o A79V7taZjgGGvuvw7XT5iecNRPtWo1r8qae5SQnlDwZqDIvQZaCq1gmftOoY3E7LSlfc1 Ou6r2fg50HXhNiAS0Z6rU5uM3spnbXbvTTVm7K6/AsXqFP70DpdL8M/4bn/3TbqmXCw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794327015; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=dlNTuczLGHrz5Am0z6YZd60IUeF4Xt5On/hEzBoyLHo=; b=iRgIiovDSUlAVxVIuDhsI1NgafKA/JXrF9l7HBgFkwDJoqAkscvvM+XUEUldQaLvYHbN JxT0DCdj72CBdWUgQwJjkzW+ksBftCrigQ6mhaCBFCin6hs3h5q8qpg4MZqZe7Xy8vOPx j31cA9DaJG43QNGN/x8aKOKO+RR9nsEqIQOyGexR8vCsxHNioOMOIPMjgEpgmsep/MC97 3aB9+itucNJrthDGyqDMqkeJIR6WvxXTB9RIi3tE75S7goTz0XwxZeGFtkoBU+2g8neYR zUDpmVq8juFLYHk/lcNpROoCts5QM4lJGTEzi6bbtCEGPuyFvQUGIYllNpIj7j8FvVg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gxyqFnbv; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E7AA260A2626 for ; Tue, 10 Nov 2026 16:10:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gxyqFnbv Received: by smtp.kernel.org (Postfix) with ESMTPSA id A177F1F008A6; Tue, 10 Nov 2026 16:10:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794327014; bh=dlNTuczLGHrz5Am0z6YZd60IUeF4Xt5On/hEzBoyLHo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gxyqFnbvauLomOurnGv3KOqdrWRsfAl4ZHfmnHUrKqN6HOxh8dRr/sDtM98sFbis+ 6pKoaO+LCCC6aMIw24G+R1tot3Xm5FwIvq1mJ3SnLzEjY4ha1azgCiyf9XoDqAhh6W XEPu+yKoCqc16C7MnoZeyO7IBMJoHME+CH4EGwG6n0ELMZTwPulp7mPyTbb9rrnbpA uIKe0k92Chh9DuXTmn6rIut10V3HzmKf3LhCLf89s4XpHMReUoAlRifYR4pF1iAM3E WxSyKw61drosQKQxeV5H3JrjCWnVShVsqJkqbZyG1/xRUO0bG5Gd/wWccDNICg9w+2 5y+i77BARVZaA== From: Sasha Levin To: stable@vger.kernel.org Cc: Krzysztof Karas , Robin Murphy , Sebastian Brzezinka , Joerg Roedel , Sasha Levin Subject: [PATCH 5.15.y] iommu/dma: Catch scatterlist length overflows Date: Tue, 10 Nov 2026 11:10:12 -0500 Message-ID: <20261110160952.2374331-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107060343-failed-5.15-1c8f6308e557@kernel.org> References: <20261107060343-failed-5.15-1c8f6308e557@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Krzysztof Karas [ Upstream commit 1c8f6308e557f32412e9d4678b3f029f47f6d9aa ] It is possible, when a very large mapping uses only one scatterlist, that padding overflows scatterlist's length field. This results in: 1) silently wrapping the value 2) smaller than desired mappings produced by iommu_map_sg 3) leaving mapped bytes in memory (no iommu_unmap) Address this issue by adding overflow detection for scatterlist length field. Fixes: 809eac54cdd6 ("iommu/dma: Implement scatterlist segment merging") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Krzysztof Karas Reviewed-by: Robin Murphy Reviewed-by: Sebastian Brzezinka Signed-off-by: Joerg Roedel [ sashal: Replaced unavailable overflows_type(s_length, s->length) with s_length > UINT_MAX. ] Signed-off-by: Sasha Levin --- drivers/iommu/dma-iommu.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index dfef5d7f5885a..d781c290f26c8 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1023,6 +1023,11 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, sg_dma_len(s) = s_length; s->offset -= s_iova_off; s_length = iova_align(iovad, s_length + s_iova_off); + if (s_length > UINT_MAX) { + ret = -EOVERFLOW; + + goto out_restore_sg; + } s->length = s_length; /* @@ -1039,7 +1044,20 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, * time through here (i.e. before it has a meaningful value). */ if (pad_len && pad_len < s_length - 1) { - prev->length += pad_len; + unsigned int new_prev_len; + + /* + * For large mappings spanning multiple GBs we + * may not be able to fit all needed padding into + * sg->length. + */ + if (check_add_overflow(prev->length, pad_len, &new_prev_len)) { + ret = -EOVERFLOW; + + goto out_restore_sg; + } + + prev->length = new_prev_len; iova_len += pad_len; } -- 2.53.0