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=-6.1 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 4D66BC43219 for ; Tue, 30 Apr 2019 11:56:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D5132075E for ; Tue, 30 Apr 2019 11:56:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556625391; bh=YLgDBj29fs5z7tKNSm5DCu3BMVVy8eo/o3FNyZrZx0U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=VsZ3r0LLahq1+jVoPyi8LB+05bB5Cev55/VlIJoxy+1+IUFu91Ah4c7lj4RMb2Ozk AccXsT4HmI2sRZLcgxMVSTImA4flUZDLCqipvmb2JPGoEj57HDnh3AV/9QHB6cc3Mm 4kuu1mXA4BgPDlenxd86Op79bi57hkrbWg/mhRoo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726166AbfD3L4Y (ORCPT ); Tue, 30 Apr 2019 07:56:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:35040 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730898AbfD3Lsr (ORCPT ); Tue, 30 Apr 2019 07:48:47 -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 C7C0820449; Tue, 30 Apr 2019 11:48:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556624926; bh=YLgDBj29fs5z7tKNSm5DCu3BMVVy8eo/o3FNyZrZx0U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dTmPl364WAVd6xgCCSpfFShEYNxpwWc4+711hb+jqeRhqx1W4Errdi7oFknazN4sA c0MOnqbcMGYwWM/Ad0ASHGyjxaS83aIuFcZlLvEL4cjpkottUqQqkCfslfkLNXqqju mFdbwqqEhCURtnJ0veSroWNa3fUMBWmE5cWEiI/U= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrea Arcangeli , Jason Gunthorpe , Leon Romanovsky Subject: [PATCH 5.0 25/89] RDMA/ucontext: Fix regression with disassociate Date: Tue, 30 Apr 2019 13:38:16 +0200 Message-Id: <20190430113611.189238783@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190430113609.741196396@linuxfoundation.org> References: <20190430113609.741196396@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Jason Gunthorpe commit 67f269b37f9b4d52c5e7f97acea26c0852e9b8a1 upstream. When this code was consolidated the intention was that the VMA would become backed by anonymous zero pages after the zap_vma_pte - however this very subtly relied on setting the vm_ops = NULL and clearing the VM_SHARED bits to transform the VMA into an anonymous VMA. Since the vm_ops was removed this broke. Now userspace gets a SIGBUS if it touches the vma after disassociation. Instead of converting the VMA to anonymous provide a fault handler that puts a zero'd page into the VMA when user-space touches it after disassociation. Cc: stable@vger.kernel.org Suggested-by: Andrea Arcangeli Fixes: 5f9794dc94f5 ("RDMA/ucontext: Add a core API for mmaping driver IO memory") Signed-off-by: Jason Gunthorpe Signed-off-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/core/uverbs.h | 1 drivers/infiniband/core/uverbs_main.c | 52 ++++++++++++++++++++++++++++++++-- 2 files changed, 50 insertions(+), 3 deletions(-) --- a/drivers/infiniband/core/uverbs.h +++ b/drivers/infiniband/core/uverbs.h @@ -160,6 +160,7 @@ struct ib_uverbs_file { struct mutex umap_lock; struct list_head umaps; + struct page *disassociate_page; struct idr idr; /* spinlock protects write access to idr */ --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -208,6 +208,9 @@ void ib_uverbs_release_file(struct kref kref_put(&file->async_file->ref, ib_uverbs_release_async_event_file); put_device(&file->device->dev); + + if (file->disassociate_page) + __free_pages(file->disassociate_page, 0); kfree(file); } @@ -876,9 +879,50 @@ static void rdma_umap_close(struct vm_ar kfree(priv); } +/* + * Once the zap_vma_ptes has been called touches to the VMA will come here and + * we return a dummy writable zero page for all the pfns. + */ +static vm_fault_t rdma_umap_fault(struct vm_fault *vmf) +{ + struct ib_uverbs_file *ufile = vmf->vma->vm_file->private_data; + struct rdma_umap_priv *priv = vmf->vma->vm_private_data; + vm_fault_t ret = 0; + + if (!priv) + return VM_FAULT_SIGBUS; + + /* Read only pages can just use the system zero page. */ + if (!(vmf->vma->vm_flags & (VM_WRITE | VM_MAYWRITE))) { + vmf->page = ZERO_PAGE(vmf->vm_start); + get_page(vmf->page); + return 0; + } + + mutex_lock(&ufile->umap_lock); + if (!ufile->disassociate_page) + ufile->disassociate_page = + alloc_pages(vmf->gfp_mask | __GFP_ZERO, 0); + + if (ufile->disassociate_page) { + /* + * This VMA is forced to always be shared so this doesn't have + * to worry about COW. + */ + vmf->page = ufile->disassociate_page; + get_page(vmf->page); + } else { + ret = VM_FAULT_SIGBUS; + } + mutex_unlock(&ufile->umap_lock); + + return ret; +} + static const struct vm_operations_struct rdma_umap_ops = { .open = rdma_umap_open, .close = rdma_umap_close, + .fault = rdma_umap_fault, }; static struct rdma_umap_priv *rdma_user_mmap_pre(struct ib_ucontext *ucontext, @@ -888,6 +932,9 @@ static struct rdma_umap_priv *rdma_user_ struct ib_uverbs_file *ufile = ucontext->ufile; struct rdma_umap_priv *priv; + if (!(vma->vm_flags & VM_SHARED)) + return ERR_PTR(-EINVAL); + if (vma->vm_end - vma->vm_start != size) return ERR_PTR(-EINVAL); @@ -991,7 +1038,7 @@ void uverbs_user_mmap_disassociate(struc * at a time to get the lock ordering right. Typically there * will only be one mm, so no big deal. */ - down_write(&mm->mmap_sem); + down_read(&mm->mmap_sem); if (!mmget_still_valid(mm)) goto skip_mm; mutex_lock(&ufile->umap_lock); @@ -1005,11 +1052,10 @@ void uverbs_user_mmap_disassociate(struc zap_vma_ptes(vma, vma->vm_start, vma->vm_end - vma->vm_start); - vma->vm_flags &= ~(VM_SHARED | VM_MAYSHARE); } mutex_unlock(&ufile->umap_lock); skip_mm: - up_write(&mm->mmap_sem); + up_read(&mm->mmap_sem); mmput(mm); } }