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=1793057089; b=u8O5TwD9DZR74ScitSWiqDicDPVIuqCKBTdypSynw2wic7KhPKLSDjb+JNVkeJOH2X6F KvA1iUJn+AikNlwMsFRhQk4ZGg7gEc50/LeNDZf3ljvkvoeGfUUQoZLEVGWDl2WJYD30R 2XAUaW2NrNIJ45nZnMujqXQe7kAO/HWsiwmtsmZdwdlOHNgUDj+bBzTEeBB7TJHIS05xQ JceTHZchCKnwq1BxrxEr6lzHK9q+xR/FZQ77VMmFuBu4VSUFywjAiBdPdsM97zTgZGHn6 3sb9lMnqvPpm0pKHSfc0HaZ9s7wHwYdq9aMiPTFe5M7CSkA1yIwKHyDb1KO3vFojMTA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793057089; 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=qQBYoODQ+YQypvvJ/bxf+QZV6zHatXlRhHg5nFuEkjY=; b=JHY+XIjnrJk2pwRHuuM7PU7H3Nf6VAmsdLDxjZ4VWM5e0siDBoiCSEMMRUJLWIP41Zm8 brloxFIpmAfsiqpD7v6y038cbvP4D3ZhSGYjNAMpDiGWi2vSjcu5Adp0vo1l+0/5sI4ae Lp+JPAdUBwzdSQ/+TOPlH00kE1dEybdGOb2aFELDkfYw9aiRpn1roeHQb6iulvILYEhup 6BRJqqkfCMAAYS6E2txP6KhboHPDuK+WVZzucQaeDrU1IKh8y6cEdstv8DpkjJwxy7B9q wfsDB28Dqevk7TMFwZbIYFH4C/o6Uk84HTRmQpZ3gy2K6+oAr0w1Ih9QlbeoXfFRUQA== 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=apiQEG5i; 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 5C275606A31A; Mon, 26 Oct 2026 23:24:49 +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=apiQEG5i Received: by smtp.kernel.org (Postfix) with ESMTPSA id E13A81F01828; Mon, 26 Oct 2026 23:24:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793057089; bh=qQBYoODQ+YQypvvJ/bxf+QZV6zHatXlRhHg5nFuEkjY=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=apiQEG5ikFEGzk70lvNqgcSuFbxsqv3KoY+cdbi/CXgRNvwDaThsY9M5RovpEEfFo JFu4/56U0E++OV3FBySS+H1tdOulH/Xt6CCEu3CGKpMEe0mUXtqJSJP9tRS6x5AJ31 m+ndyvHcLpq9OAW6nIACsnOC6HrvGmJMoMlpGQYK/jThBCwuCcSKNUEAxCW5t7xDNB fMVR4TiZ2J0xQ9Jvws7WPcLF4R7Nvdr7TVW1if1FFkP9Mbip4u6YJm2tr3KsE9sF6z xzpiQJB5NBcKKSuheBGTIIOW8lkxwrcHd257sDU9t8MbpXu6q2KjpsZ0YlL42ux0QL GAcroa840G2Qg== From: "David Hildenbrand (Arm)" Date: Tue, 27 Oct 2026 00:17:42 +0100 Subject: [PATCH 22/46] mm/gup: check for overflow when converting nr_pages to bytes in GUP-fast X-Mailing-List: linux-kernel@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: <20261027-fixes_core-v1-22-6f74bec9a5bb@kernel.org> References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> In-Reply-To: <20261027-fixes_core-v1-0-6f74bec9a5bb@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=1166; i=david@kernel.org; h=from:subject:message-id; bh=xmWshrb3+Xou48CaDcjPkXm82MkuoZo6NmHK5/nuQPc=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLu35+aeTNfcdI97pS5wQm7FPTWmh1Unr01g9eJPX+Bl UAIt9SGjlIWBjEOBlkxRZag4PsGL1+uq61242OGmcPKBDKEgYtTACbCtYDhn2Fw+YTli4MZd/M1 hdXvvvO+YDZr6cVrBREH3i/9tpjT9AfD/1Q724PTdmWLiq3IYFMDOiS8cHKfUes+/QXfD+c+fba OCQA= 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 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 9906965893431..48e1bfe5ab9a9 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -3214,8 +3214,8 @@ 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