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=1794420279; b=G7lVJHjrFn3nx+XOfIk23AHAkv1Zjki9t4TXkCnyXbNwAFqG36FOrbYmanTQZtjmHaBq 23ErUOlHHCnyzzlTKaKMHqO6Bu7AlEjNKrhCP5xh67LsX+U+am8l7qmpcBMXNrg1eeCB1 /ZryOyBNjuhqPMJwpBEn5X0MO3b0OTyFbWhjy6dkbpyFuCyvWXL3FE/OUrVjMt1y9HUBL JnaMqMe+/2nk09R0c3CFEB77dTBAXjdrnLUij74880+71F10cwcMOYNL9yXw4S7FSb3MK z+TyMDydtmURlC4WrOGkAaOe4ZKMs6RI82dqD/419qGl4rrQGZqBiBHv/KiFuwDXa2A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794420279; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=8flrmTNlp7L2C3bdjz0v5JpZBMdtc8AegGYpyk6AJX8=; b=cdioLvOQSFLogE0FZnvyuUrwErVXD4GCtGLTGA41T39mW+sA1Za0hYBs68vO4DOj3YJc QznrC6tuk0Ym6v3Wk1ribtm71yZTQKFgxiJXD7HyujoivOlVfMeill66yDqek4d52Yfq8 SlS1MCNl8FvTYk7rEase8ZE2xf/BEmg06hFK+BOB3JWk5V2yom+vSm7I2A5zu4iRwG8pU qjnE5al5EEtyh4O9eMPfp9aiRpGwRgadBbZa0gBgDByrk2QdoLhi8qpJxnSXqZXc0/GnR DeXcEbjzByubjZXmgH0KPrUfxhK0fwPyBq66XX3dLYAA/DjL3krx0giW7pVe/INtVUA== 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=Kqu6hEX1; 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 9345A606A321 for ; Wed, 11 Nov 2026 18:04:39 +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=Kqu6hEX1 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F3911F00A0A; Wed, 11 Nov 2026 18:04:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794420279; bh=8flrmTNlp7L2C3bdjz0v5JpZBMdtc8AegGYpyk6AJX8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Kqu6hEX1A3LqjIjZRWNVSeaNy31vWAzZdp6phyB/VSIweWJQieuviN8CoruBwv2l2 bFqRdF2xHYyf3ETrIRiZiiovq67rnzLABtCQHAMo2ic1f286TyvpZgR6mgRoYX7o2b 67y5eu/TbNSVSm7OyXOvQYcCUhsVwW1fy+VELrt0gZuz57u23lHEDb2WVirMP96ghY znoj3vRsnyFxh+pPlpy9YpzZ9z3GLNt+XfyLoeOheO4jthK8NJw5Jqq8cxrlO/tCY+ PG5hPYFOTYn6SLHPsDnM55Hl6BAJCYozkZ/PwQzc2tykZes157eCVxKJu4102stCZb 96CXvkZ3Uhd1Q== From: Sasha Levin To: stable@vger.kernel.org Cc: "David Hildenbrand (Arm)" , "Lorenzo Stoakes (ARM)" , Muchun Song , Barry Song , Muhammad Usama Anjum , Sasha Levin Subject: [PATCH 6.1.y] mm/gup: check for overflow when converting nr_pages to bytes in GUP-fast Date: Wed, 11 Nov 2026 13:04:37 -0500 Message-ID: <20261111180419.3728532-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109201826-failed-6.1-21a3888d3d2f@kernel.org> References: <20261109201826-failed-6.1-21a3888d3d2f@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: "David Hildenbrand (Arm)" [ Upstream commit 21a3888d3d2f87b7f15ccea1f0befd57346fe899 ] 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 Link: https://patch.msgid.link/20261031-fixes_core-v3-22-d6437171ecc3@kernel.org Signed-off-by: David Hildenbrand (Arm) [ sashal: adapted gup_fast_fallback() changes to internal_get_user_pages_fast() ] Signed-off-by: Sasha Levin --- mm/gup.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index b3b6de2c37c12..8629b2e145460 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -3065,9 +3065,9 @@ static int internal_get_user_pages_fast(unsigned long start, 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)) - return 0; + if (check_shl_overflow(nr_pages, PAGE_SHIFT, &len) || + check_add_overflow(start, len, &end)) + return -EOVERFLOW; if (unlikely(!access_ok((void __user *)start, len))) return -EFAULT; -- 2.53.0