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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9BB34C433DF for ; Mon, 20 Jul 2020 12:17:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 797F322B4D for ; Mon, 20 Jul 2020 12:17:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595247440; bh=uQV7p4DDykWaaEJLgcFwY/f86K0qe6na9NHJqSsn9Fg=; h=Subject:To:Cc:From:Date:List-ID:From; b=Lc5hg1FOYC+OKRzrplUASM29kzs65exzeduaUanHiSsTOi9yAPCqS7jgyDvfLY+l/ bvHkRJghuNLWdk+Hv6UoctBQOxXaSyjlfa4DXMSy69T+QqInHMVb3yF3dmrgs/289n O3F8+af+/8gkyNSYwwR8H9QCUwkk5gdvB6PkbzWY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728601AbgGTMRU (ORCPT ); Mon, 20 Jul 2020 08:17:20 -0400 Received: from forward5-smtp.messagingengine.com ([66.111.4.239]:56543 "EHLO forward5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728564AbgGTMRT (ORCPT ); Mon, 20 Jul 2020 08:17:19 -0400 Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailforward.nyi.internal (Postfix) with ESMTP id 7D93D1941116; Mon, 20 Jul 2020 08:17:18 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute1.internal (MEProxy); Mon, 20 Jul 2020 08:17:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=nKZb7N bdXCfw7b7KfFhj8C+v2mczaXWCvfrynKQDQZY=; b=S2XzFE/fFnt8OxjUpuM7xK 0ZQLWO1HIRcY1pmMUNTFVkg2KvfBF+3YBSwejE8FmRyLZQlveCHog9jzhaAGWuq+ DGysqD1F4qSVerXNZX9M7D8ZEv+F0NPoPfhWQNS8lP5YNb0cbk4tPtPwFOrMDrCh 0eDYbjKNPZeD25EzciqOkecx9smasftoKswK41GZ/sEYcT5+Z/nqwmbk4qP4nBE8 6S9I5vtSSRXDHwp8av1bGrf+rj2vS+Nx196Yj5CNw4xVUhpWW0F3cwHrA6X7LibW ennMaxfPVWsAKSoV+uY2EOWfFZULChdmW6/rbjr97zA1KjBsZyRA8Gxj8TsHsaiQ == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduiedrgeeggddvhecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecunecujfgurhepuffvhfffkfggtgfgsehtkeertddttd ejnecuhfhrohhmpeeoghhrvghgkhhhsehlihhnuhigfhhouhhnuggrthhiohhnrdhorhhg qeenucggtffrrghtthgvrhhnpedvffegjeejiedtieffjeeijeffgfehvdeiudejheefge evhffhvedvfeeuheekleenucffohhmrghinhepfhhrvggvuggvshhkthhophdrohhrghen ucfkphepkeefrdekiedrkeelrddutdejnecuvehluhhsthgvrhfuihiivgeptdenucfrrg hrrghmpehmrghilhhfrhhomhepghhrvghgsehkrhhorghhrdgtohhm X-ME-Proxy: Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) by mail.messagingengine.com (Postfix) with ESMTPA id 3D3B43060067; Mon, 20 Jul 2020 08:17:17 -0400 (EDT) Subject: FAILED: patch "[PATCH] dmabuf: use spinlock to access dmabuf->name" failed to apply to 5.4-stable tree To: charante@codeaurora.org, christian.koenig@amd.com, michael.j.ruhl@intel.com, stable@vger.kernel.org, sumit.semwal@linaro.org Cc: From: Date: Mon, 20 Jul 2020 14:17:26 +0200 Message-ID: <15952474469367@kroah.com> 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 The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6348dd291e3653534a9e28e6917569bc9967b35b Mon Sep 17 00:00:00 2001 From: Charan Teja Kalla Date: Fri, 19 Jun 2020 17:27:19 +0530 Subject: [PATCH] dmabuf: use spinlock to access dmabuf->name MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There exists a sleep-while-atomic bug while accessing the dmabuf->name under mutex in the dmabuffs_dname(). This is caused from the SELinux permissions checks on a process where it tries to validate the inherited files from fork() by traversing them through iterate_fd() (which traverse files under spin_lock) and call match_file(security/selinux/hooks.c) where the permission checks happen. This audit information is logged using dump_common_audit_data() where it calls d_path() to get the file path name. If the file check happen on the dmabuf's fd, then it ends up in ->dmabuffs_dname() and use mutex to access dmabuf->name. The flow will be like below: flush_unauthorized_files() iterate_fd() spin_lock() --> Start of the atomic section. match_file() file_has_perm() avc_has_perm() avc_audit() slow_avc_audit() common_lsm_audit() dump_common_audit_data() audit_log_d_path() d_path() dmabuffs_dname() mutex_lock()--> Sleep while atomic. Call trace captured (on 4.19 kernels) is below: ___might_sleep+0x204/0x208 __might_sleep+0x50/0x88 __mutex_lock_common+0x5c/0x1068 __mutex_lock_common+0x5c/0x1068 mutex_lock_nested+0x40/0x50 dmabuffs_dname+0xa0/0x170 d_path+0x84/0x290 audit_log_d_path+0x74/0x130 common_lsm_audit+0x334/0x6e8 slow_avc_audit+0xb8/0xf8 avc_has_perm+0x154/0x218 file_has_perm+0x70/0x180 match_file+0x60/0x78 iterate_fd+0x128/0x168 selinux_bprm_committing_creds+0x178/0x248 security_bprm_committing_creds+0x30/0x48 install_exec_creds+0x1c/0x68 load_elf_binary+0x3a4/0x14e0 search_binary_handler+0xb0/0x1e0 So, use spinlock to access dmabuf->name to avoid sleep-while-atomic. Cc: [5.3+] Signed-off-by: Charan Teja Kalla Reviewed-by: Michael J. Ruhl Acked-by: Christian König [sumits: added comment to spinlock_t definition to avoid warning] Signed-off-by: Sumit Semwal Link: https://patchwork.freedesktop.org/patch/msgid/a83e7f0d-4e54-9848-4b58-e1acdbe06735@codeaurora.org diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 412629601ad3..1ca609f66fdf 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -45,10 +45,10 @@ static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen) size_t ret = 0; dmabuf = dentry->d_fsdata; - dma_resv_lock(dmabuf->resv, NULL); + spin_lock(&dmabuf->name_lock); if (dmabuf->name) ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN); - dma_resv_unlock(dmabuf->resv); + spin_unlock(&dmabuf->name_lock); return dynamic_dname(dentry, buffer, buflen, "/%s:%s", dentry->d_name.name, ret > 0 ? name : ""); @@ -338,8 +338,10 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf) kfree(name); goto out_unlock; } + spin_lock(&dmabuf->name_lock); kfree(dmabuf->name); dmabuf->name = name; + spin_unlock(&dmabuf->name_lock); out_unlock: dma_resv_unlock(dmabuf->resv); @@ -402,10 +404,10 @@ static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file) /* Don't count the temporary reference taken inside procfs seq_show */ seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1); seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name); - dma_resv_lock(dmabuf->resv, NULL); + spin_lock(&dmabuf->name_lock); if (dmabuf->name) seq_printf(m, "name:\t%s\n", dmabuf->name); - dma_resv_unlock(dmabuf->resv); + spin_unlock(&dmabuf->name_lock); } static const struct file_operations dma_buf_fops = { @@ -542,6 +544,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) dmabuf->size = exp_info->size; dmabuf->exp_name = exp_info->exp_name; dmabuf->owner = exp_info->owner; + spin_lock_init(&dmabuf->name_lock); init_waitqueue_head(&dmabuf->poll); dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll; dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0; diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index ab0c156abee6..a2ca294eaebe 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -311,6 +311,7 @@ struct dma_buf { void *vmap_ptr; const char *exp_name; const char *name; + spinlock_t name_lock; /* spinlock to protect name access */ struct module *owner; struct list_head list_node; void *priv;