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=1793439958; b=GuPqHZ6DuCSTvn1iIz4L41420U7eUK1oCg36EyKUZyU90ROCeSNZRZUCZi3m8NrGqvKZ 0BhmphzxKXagh50iHZUW303Opd693L89h6aGqhpdRI/ZGVJ1v0bKXJyFFqG5BLPgaVXP2 SZNPiyhyBW05AcL8wyNWFFLYwj39FJYsCfVR/Z7pqdZRP0Vsohmou1s2AOfm6pA0Otcbr dxL6TTqkc+j+uDeQAGLvfMt5L1Q2YcxEdVt4F1a/+dLUIBcAEaAl2U538ptI67qUEiHmS mDjIvrBXczmgq2tFPWc7RQO7Wdn9GAVPgjSnbNCjQq59rAVC7mkrklBOz5/ArX7nfrA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793439958; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=wISwi351T9RVVV1oXeQonBfVyTKFfK4XoWM4mZGU1z8=; b=NsfYYEiD+gaO4EB1Aj8Cb8WY8TJ/peSvj5yMU6H9rDRb9MowlRdkXjud5K1W52mqC009 phiAw04qR3bEtjbZt6qxr9cJdvLTcVd8kEY1drRqBmI/3MYI8tOH/NeZs6pn5zVrAAHy9 SvakRO/0A3gQZKqkTcZGG7Br10Ymfe+T3ME2iiDEDA1agt1X27B0w4Hzxr65MjboWBjtS XYgaarVHQ7y2/m2yILqSP93B6eK+OniQYTbAJMOOcNaA+X3aker0PDqmApKZf7AikA3ZS wLrhxZMrbsjGf+xHBzYitF5sR7NFh6zOBXvoFVRj7X5XRTcGkES1z2gFoqnk8QnxguQ== 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="OcVH/BeE"; 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 2E7DD606A320; Sat, 31 Oct 2026 09:45:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OcVH/BeE Received: by smtp.kernel.org (Postfix) with ESMTPSA id 278111F0093A; Sat, 31 Oct 2026 09:45:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793439957; bh=wISwi351T9RVVV1oXeQonBfVyTKFfK4XoWM4mZGU1z8=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=OcVH/BeEc2hYfL2FYGWe1OvmH8o+k5edNc4FHDUjc8QmLWMD9qEaA3739kvUYuIIv NdEhiB4tuErpPCysmctpgOwiA1RyjWRiKmEBs4q/oO0aFyWb6QW2imFkeevKJ6/u6/ A5D7ccuqBCziN4Gk+eR3salFGBi6bsDi9+pKQkmS4CuDSUFnOvvuZSPJhGkhtRUJuz hyaWctchXf7KHnMJMYfXCPdeKm59BqQ5oSysl9esxUiYfV5qJnQm09ojPLZu36HExp qeaPCo7g8Ah2K2QCxL85rqYn6+orFN7B2pkZTZuUAVM5jv2YS9eLZFOLhcs/7mIU3w 4zHQWM0WMBKFA== From: "David Hildenbrand (Arm)" Date: Sat, 31 Oct 2026 10:39:51 +0100 Subject: [PATCH v3 22/47] mm/gup: check for overflow when converting nr_pages to bytes in GUP-fast X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261031-fixes_core-v3-22-d6437171ecc3@kernel.org> References: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> In-Reply-To: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> To: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, Muhammad Usama Anjum , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1366; i=david@kernel.org; h=from:subject:message-id; bh=kuHYCo8jZXAQ9XN8vjw93pI/nGqY4DS2NH2YO8khoeQ=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLKebs94vWxtqPbuuB9vUk9tOlh+p4nLJ3bzr5mJJZUfV U4vWNkT0VHKwiDGwSArpsgSFHzf4OXLdbXVbnzMMHNYmUCGMHBxCsBEtM8zMqzlOOtfm5t343jZ 1o5lDTYVTDu850yesrHneqye5kuf74sZ/leL5UluV9b4zxeU2FBTZ/1S7rP6zpebP1huXfhOy1z gLQcA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A The overflow check in gup_fast_fallback() only covers the addition to start. The preceding nr_pages << PAGE_SHIFT can already have truncated the length on 32bit. Users such as RapidIO's rio_dma_transfer() can derive such page counts from a 64-bit userspace length. Let's just check_shl_overflow() to reject any such overflow with -EOVERFLOW early. Fixes: c28b1fc70390 ("mm/gup: reorganize internal_get_user_pages_fast()") Cc: stable@vger.kernel.org Reviewed-by: Lorenzo Stoakes (ARM) Acked-by: Muchun Song Reviewed-by: Barry Song Tested-by: Muhammad Usama Anjum Signed-off-by: David Hildenbrand (Arm) --- mm/gup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 1c2ac7c66c309..ba4907b352323 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -3225,8 +3225,8 @@ static int gup_fast_fallback(unsigned long start, unsigned long nr_pages, might_lock_read(¤t->mm->mmap_lock); start = untagged_addr(start) & PAGE_MASK; - len = nr_pages << PAGE_SHIFT; - if (check_add_overflow(start, len, &end)) + if (check_shl_overflow(nr_pages, PAGE_SHIFT, &len) || + check_add_overflow(start, len, &end)) return -EOVERFLOW; if (end > TASK_SIZE_MAX) return -EFAULT; -- 2.43.0