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=1794327995; b=A3/1R07FsLNJF0Vg3fhVCO+Rj7pmZ8xo/2bAdTGRW8K8FO3YcIL0BiBYq1Q85OfL5Xdr DmaSAInQOcnq/vERDVOYZFghZvx+cc4q8Hgaq3xzp0QcN9cYdwm5PBNWG6esXTCWVJLyq YK+Cn1g5k7oGVG4Q/rYQ2B7An9H47G78L84yni6PZ4V+Id8/qC1N7KM/L+ZW3XKa+bdHA 3oIzKMCfwC6kIn93HkGKmES0tiUciqFgctd+z4ZoII/zxMCeKW0BM6zrjNzPssFp9ZY31 wxbIv53rH9LEAmwLRONlSFgJmDsQesFgAFft+mZjmvCvVqcx7Z3+SOHzpdytXew7knA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794327995; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=lI1fjWdnZj7GJO4o3WwU9IdBvoMbfrGdNk/WBV4xtLA=; b=XyVLKX8S0/43y84sqdONakgl+yC5CdZFDOHz+5gD/M16BRLfnV7uTRZfpD7/0s31X6pl tXRfrEpCEQruoPfe4zXxFHVXyXrQEw06gmw1E4T1c9Kxp0tn3wgxPLTpDCuYnG8J+WrUN BRFJ4miPqvysd5N3gWznl/dY5zbaoybqYlhyC4Salbsz8LXlE9cvCczM6ROy4gXVdFVVg jgFZFvWsXqRJOYdqVy++oaNzK+pfUoA12rlpZJ03USIIixYdnCO8mwha5u7oI4fcxLiAH pn5atAC2u+rlwqXv4YVYgdNu4/0pWjJc4IaqssZCbMui1Wyo94dG+E8E8N7TMKQpDOA== 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=jmQONUgQ; 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 1268C606A320 for ; Tue, 10 Nov 2026 16:26:34 +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=jmQONUgQ Received: by smtp.kernel.org (Postfix) with ESMTPSA id D66971F0089F; Tue, 10 Nov 2026 16:26:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794327994; bh=lI1fjWdnZj7GJO4o3WwU9IdBvoMbfrGdNk/WBV4xtLA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jmQONUgQSLebWBnc+grzh8uL4PRkSK6mFh2zwLOIxdBe3LRiNmZHXv9CUPU+ZKdNn 6DnYHQw/iNlJqZU4zLJUJR1jnejCFky97jsFKN7WQncD/U9SZsGrU7VHJZKfoKbcAX qkfNHFDz8smPcB4VokQAxmKMt7u7a0/km9A7aYG7BEs1hufvhJzmoWtDExcBdkgJTw ci00blV67RiS6BV0LFLSzaoIETCMfW6EMXv9KepMYTDirS3U8gqRkXQkm1zvteY676 ACnSoBu+/8Uum7l+hLqsIb1hR7GHijtHPpDTc0t8tcfMEmYJhGY3jDAR6nO4K72XuA WuvrEJtFeaS/A== From: Sasha Levin To: stable@vger.kernel.org Cc: Krzysztof Karas , Robin Murphy , Sebastian Brzezinka , Joerg Roedel , Sasha Levin Subject: [PATCH 5.10.y] iommu/dma: Catch scatterlist length overflows Date: Tue, 10 Nov 2026 11:26:32 -0500 Message-ID: <20261110162514.2440239-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107062022-failed-5.10-1c8f6308e557@kernel.org> References: <20261107062022-failed-5.10-1c8f6308e557@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: adapted overflow handling to use an unsigned int cast comparison while preserving zero-on-failure returns ] Signed-off-by: Sasha Levin --- drivers/iommu/dma-iommu.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 62dd195d88062..321c2f34de4dc 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -864,6 +864,8 @@ 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 != (unsigned int)s_length) + goto out_restore_sg; s->length = s_length; /* @@ -880,7 +882,17 @@ 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)) + goto out_restore_sg; + + prev->length = new_prev_len; iova_len += pad_len; } -- 2.53.0