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=1794326006; b=G/XbkM8StnslPit3OqHhmA9M544fAypEpksdl21BRbRnCoFyOnemYCnDrQ2PZNpxwE4w cb/Z5FfNR18httY5Qc57R0gLKgImfGX9cEmSCimRCwok6D0a77MwOANml1jfgeKGvHAMg R9VsbPtSU2vrTNKk8braFpBovYxVJxsg63ba1R0n/osyU1eShLFbE6vY7TcVCzc6Fbahk +Hts5nhgKgi6vqjLebuCwR7DzJ+4Xz7KiUhIXbMEWt54VHhJn97KCSA1+rbhByYvaCagl t32IIjgeLicqeV0FXysUXED2ldScbFhbkLqlwPpFtzddQPNvSPEF+DLKqODqQHh3H9A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794326006; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=sJhOzefKyOEL9GGEHxAz3IoMEZaq1foMkZC7vE5/6v4=; b=WxF+ELLC/aXpFyrlhciKwJVgciNJTTlM6B4ji1e1Itcj/jE/cPlfq+zJc1tZ1Yj4wnDE SSSHwDIVAv+26jNaVvzmKtSIbOfHXVHMcsIP5RrVHSbecvQSuiSZVdOjOWMjyYVyTZ4fO 5j61dOswZGE4lrEsF/xIrHJeLhhFFnzqSWiFABUvkiLnmLkbBnQxnVp77Lr3LybocfBvv Jo7X6dE/g22AbXz/QWIC5mQ+esKpiECize1uedwDk+OxojyCOzb8cW18QYpZZ1dxCo3Eu 7TCPU8QN9uOmV21Wh34tvVDIBIhT5gB1AHHjvW2CP+hEqMBP0YRmWbOAQi3IJVv3Eww== 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=OWwKYa8s; 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 7DB62606A32D for ; Tue, 10 Nov 2026 15:53:26 +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=OWwKYa8s Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65EBF1F008A1; Tue, 10 Nov 2026 15:53:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794326006; bh=sJhOzefKyOEL9GGEHxAz3IoMEZaq1foMkZC7vE5/6v4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OWwKYa8sUmVs1XHmhY0WrDeha6V9Obj3qUK1n8DkB5m5Mqk5xBLQve98177VPmvG+ WD3M9KLebAHULP2pRpdmbpp0EL2LDHenWCPYa7E8+5PQbN9QlLexSwiemGSCxWuc1J txaBy6qzM+1LhxSkhAxbWQoq4cYuRTOkT+kZqAv0PiWjtDh5J+xqnQE7bvNVJfJ+0d 3PxWXkGEZGqmpPuQXgpAxpkrmHrKfOZOrjF5i5OAafgLzD2tc3SYNHnymxW14JBSKH CHQIzLqSYhwio5huC0mNJryzms7cusHjmVMKFZUlhI87tPujgKgwL7E7AyfQmurKId /AiKHSWKekXAQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Krzysztof Karas , Robin Murphy , Sebastian Brzezinka , Joerg Roedel , Sasha Levin Subject: [PATCH 6.1.y 2/2] iommu/dma: Catch scatterlist length overflows Date: Tue, 10 Nov 2026 10:53:22 -0500 Message-ID: <20261110155252.2304363-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261110155252.2304363-1-sashal@kernel.org> References: <20261107054614-failed-6.1-1c8f6308e557@kernel.org> <20261110155252.2304363-1-sashal@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 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 c3e5f9a435ffb..3ac8faeef67ba 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1250,6 +1250,11 @@ 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 (overflows_type(s_length, s->length)) { + ret = -EOVERFLOW; + + goto out_restore_sg; + } s->length = s_length; /* @@ -1266,7 +1271,20 @@ 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