From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75DCDC43381 for ; Fri, 22 Mar 2019 12:40:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40D7A2190A for ; Fri, 22 Mar 2019 12:40:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553258428; bh=6KfBVJ3m5R21fDxFjxoQkNsL8x1SKclXLwAXu2VGBG4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=WcdiKiJoz4rF1m1LueX+ktN7h9zX1ds0ChhJMKOp7ZIt353GAvDOR/N5eoRWfHjxf rnizwMfNK7Y2We0EyzTZzhk00iihfBcGm7VL7/3/Lxh7Rtycg+MhigftbcwFnjzu/Z PjTBaD2h1DamjnnLEzCyjE8xukmuYafZGB/dursk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388244AbfCVMkV (ORCPT ); Fri, 22 Mar 2019 08:40:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:45204 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388228AbfCVMGp (ORCPT ); Fri, 22 Mar 2019 08:06:45 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7D997206C0; Fri, 22 Mar 2019 12:06:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553256405; bh=6KfBVJ3m5R21fDxFjxoQkNsL8x1SKclXLwAXu2VGBG4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IACnXoVll7qIwbf348E691pmZGuFHNfZolL4HMwR/amnsr+j+qQ9Tn5IBmyVTRrBA vQ30cN+ZIED8ulOdqvUjV9zhOKq2T8MYV3bt+7rg/TKK1vZMrCda+buv0Y+ILewwvK n4/Vh0WFSMHRhDkc1DCiLiVWjmvBpYeUAegx9QDY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Roman Penyaev , Michal Hocko , Andrey Ryabinin , Joe Perches , "Luis R. Rodriguez" , Andrew Morton , Linus Torvalds Subject: [PATCH 4.19 201/280] mm/vmalloc: fix size check for remap_vmalloc_range_partial() Date: Fri, 22 Mar 2019 12:15:54 +0100 Message-Id: <20190322111330.764404978@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111306.356185024@linuxfoundation.org> References: <20190322111306.356185024@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Roman Penyaev commit 401592d2e095947344e10ec0623adbcd58934dd4 upstream. When VM_NO_GUARD is not set area->size includes adjacent guard page, thus for correct size checking get_vm_area_size() should be used, but not area->size. This fixes possible kernel oops when userspace tries to mmap an area on 1 page bigger than was allocated by vmalloc_user() call: the size check inside remap_vmalloc_range_partial() accounts non-existing guard page also, so check successfully passes but vmalloc_to_page() returns NULL (guard page does not physically exist). The following code pattern example should trigger an oops: static int oops_mmap(struct file *file, struct vm_area_struct *vma) { void *mem; mem = vmalloc_user(4096); BUG_ON(!mem); /* Do not care about mem leak */ return remap_vmalloc_range(vma, mem, 0); } And userspace simply mmaps size + PAGE_SIZE: mmap(NULL, 8192, PROT_WRITE|PROT_READ, MAP_PRIVATE, fd, 0); Possible candidates for oops which do not have any explicit size checks: *** drivers/media/usb/stkwebcam/stk-webcam.c: v4l_stk_mmap[789] ret = remap_vmalloc_range(vma, sbuf->buffer, 0); Or the following one: *** drivers/video/fbdev/core/fbmem.c static int fb_mmap(struct file *file, struct vm_area_struct * vma) ... res = fb->fb_mmap(info, vma); Where fb_mmap callback calls remap_vmalloc_range() directly without any explicit checks: *** drivers/video/fbdev/vfb.c static int vfb_mmap(struct fb_info *info, struct vm_area_struct *vma) { return remap_vmalloc_range(vma, (void *)info->fix.smem_start, vma->vm_pgoff); } Link: http://lkml.kernel.org/r/20190103145954.16942-2-rpenyaev@suse.de Signed-off-by: Roman Penyaev Acked-by: Michal Hocko Cc: Andrey Ryabinin Cc: Joe Perches Cc: "Luis R. Rodriguez" Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/vmalloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2244,7 +2244,7 @@ int remap_vmalloc_range_partial(struct v if (!(area->flags & VM_USERMAP)) return -EINVAL; - if (kaddr + size > area->addr + area->size) + if (kaddr + size > area->addr + get_vm_area_size(area)) return -EINVAL; do {