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=1793306335; b=cZDkeryoEOPSD0y2IlUK4BJq26RmfZhmM4efGIuiot8S+DYnltJJP3TnEoLFDqngbqQe IXip9+LYZW2cXWy2f34ayKv8id043z66bb7A6Ium4dU1x0/Vlnv5oAIi407UWRz2iZLGD /IK/W8l5gMGvyCcPaTOK7564Gp7/wU4fYYs3Hg8QLjrSZ4PhMyYUsGMijFQY0jQem0zJm gfALeC3UdeVZzSqpS5uHenRJpT6QKm5fKUc/5Vm+KhGvMb23J1tWZhsZmetBRnJnv6Rdj VXwQXEtSVeqiWykrqOW1KVM4es1+3Uz818VikfUhUTPF70+5leHhiexT8Zow9ofDnbw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793306335; 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=VnQ13mkoh6ozIDWGTVX+C6HT4vjQEoXrCm0MooEO04s=; b=x5G6j4+oajXW1nWzU5i+yrPcLKqA4wyBKiZF2igE3jESJ+V9uVwlVNjkhXPGyrig/Ma2 kHkdut2uNg6wnyx1Kr+wcYvG6tqC1/EvsMqx8tXhFdmul6uWorWXiaZD6cSuX07rXgDy5 nBpcDeVhc5uvlGFlNo/ysCIp0/tRnBKy40u0I1XeXHZ62/eiFlb1jhaaOodhxbVLr+WBS /yL79FDl1e8w4ASDANcfjj48L+AAj0e/lXEy2d2KteDRmT/p85heK0zGKMdVVBwFJ1s31 v04nEAf1j89oleUxU7EvsAerPdpmJIa6hilD2q18CqJVFucauIiQVVbX6y1o8YR8ZYw== 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=YezDjZU2; 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 B6B0B606A31E; Thu, 29 Oct 2026 20:38:54 +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=YezDjZU2 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 736391F01829; Thu, 29 Oct 2026 20:38:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306334; bh=VnQ13mkoh6ozIDWGTVX+C6HT4vjQEoXrCm0MooEO04s=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=YezDjZU2yi5cWmUqfDHysvLO9HwSd76jRjz2DKKiJKmvX5TchaYVydd2c1v8z1JoG ukY6PBjO2jSZ2MQea3k0Ss09Ud/uCHu5P7yCWtRSy256Tb4AzyVTKkJiiDAcgduQg7 xrppl9xLjFoWu1REw195bMUI8zpRl7qt7xONHzxWgUiB25CSuIO+I9FXJAhMAXvIxe 9vFj0edvZ4NkCIz0Xn+Jfn8csY2hF2LHytvnUSwkq/J8TpxTtMH2yoRQoiT7o4M8eY 68bluiNVhI3XJ1TLn1f1fRogMry8mga7lzsNOhsJevsO9wM1nRRKTRUXOiJoCR3V2/ aAjnkIfXbMGHA== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:17 +0100 Subject: [PATCH v2 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: <20261029-fixes_core-v2-22-a64ce7f83abb@kernel.org> References: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> In-Reply-To: <20261029-fixes_core-v2-0-a64ce7f83abb@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, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1309; i=david@kernel.org; h=from:subject:message-id; bh=1C5sa/S2cZ8sLgA0w/Gi6tvhiudETPPmM19hS9JNC5Q=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer21vLdw0040r6ZRnZU1d3rZlDw/pO7lrXgmoYp4wY /tajl38HaUsDGIcDLJiiixBwfcNXr5cV1vtxscMM4eVCWQIAxenAEzEYTkjw+vlHL3B1hunvHr1 /9a717nmGp87rIONvDT4+Q4o6P65soKRofVY6M6Jcm9fbfnHGVBQEHrm94n22fOMc+78Cd67bJV 1FjcA 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 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 1c2ac7c66c30..ba4907b35232 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