Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751346AbdCYVjA (ORCPT ); Sat, 25 Mar 2017 17:39:00 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:35504 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750903AbdCYVi4 (ORCPT ); Sat, 25 Mar 2017 17:38:56 -0400 From: Mike Kravetz To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Tetsuo Handa , Michal Hocko , Hillf Danton , Dave Hansen , Andrew Morton , Mike Kravetz Subject: [PATCH v2] hugetlbfs: initialize shared policy as part of inode allocation Date: Sat, 25 Mar 2017 14:37:30 -0700 Message-Id: <1490477850-7944-1-git-send-email-mike.kravetz@oracle.com> X-Mailer: git-send-email 2.7.4 X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4875 Lines: 118 Any time after inode allocation, destroy_inode can be called. The hugetlbfs inode contains a shared_policy structure, and mpol_free_shared_policy is unconditionally called as part of hugetlbfs_destroy_inode. Initialize the policy as part of inode allocation so that any quick (error path) calls to destroy_inode will be handed an initialized policy. syzkaller fuzzer found this bug, that resulted in the following: BUG: KASAN: user-memory-access in atomic_inc include/asm-generic/atomic-instrumented.h:87 [inline] at addr 000000131730bd7a BUG: KASAN: user-memory-access in __lock_acquire+0x21a/0x3a80 kernel/locking/lockdep.c:3239 at addr 000000131730bd7a Write of size 4 by task syz-executor6/14086 CPU: 3 PID: 14086 Comm: syz-executor6 Not tainted 4.11.0-rc3+ #364 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x1b8/0x28d lib/dump_stack.c:52 kasan_report_error mm/kasan/report.c:291 [inline] kasan_report.part.2+0x34a/0x480 mm/kasan/report.c:316 kasan_report+0x21/0x30 mm/kasan/report.c:303 check_memory_region_inline mm/kasan/kasan.c:326 [inline] check_memory_region+0x137/0x190 mm/kasan/kasan.c:333 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:344 atomic_inc include/asm-generic/atomic-instrumented.h:87 [inline] __lock_acquire+0x21a/0x3a80 kernel/locking/lockdep.c:3239 lock_acquire+0x1ee/0x590 kernel/locking/lockdep.c:3762 __raw_write_lock include/linux/rwlock_api_smp.h:210 [inline] _raw_write_lock+0x33/0x50 kernel/locking/spinlock.c:295 mpol_free_shared_policy+0x43/0xb0 mm/mempolicy.c:2536 hugetlbfs_destroy_inode+0xca/0x120 fs/hugetlbfs/inode.c:952 alloc_inode+0x10d/0x180 fs/inode.c:216 new_inode_pseudo+0x69/0x190 fs/inode.c:889 new_inode+0x1c/0x40 fs/inode.c:918 hugetlbfs_get_inode+0x40/0x420 fs/hugetlbfs/inode.c:734 hugetlb_file_setup+0x329/0x9f0 fs/hugetlbfs/inode.c:1282 newseg+0x422/0xd30 ipc/shm.c:575 ipcget_new ipc/util.c:285 [inline] ipcget+0x21e/0x580 ipc/util.c:639 SYSC_shmget ipc/shm.c:673 [inline] SyS_shmget+0x158/0x230 ipc/shm.c:657 entry_SYSCALL_64_fastpath+0x1f/0xc2 Analysis provided by Tetsuo Handa v2: Remove now redundant initialization in hugetlbfs_get_root Reported-by: Dmitry Vyukov Signed-off-by: Mike Kravetz --- fs/hugetlbfs/inode.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 54de77e..cf3669d 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -695,14 +695,11 @@ static struct inode *hugetlbfs_get_root(struct super_block *sb, inode = new_inode(sb); if (inode) { - struct hugetlbfs_inode_info *info; inode->i_ino = get_next_ino(); inode->i_mode = S_IFDIR | config->mode; inode->i_uid = config->uid; inode->i_gid = config->gid; inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); - info = HUGETLBFS_I(inode); - mpol_shared_policy_init(&info->policy, NULL); inode->i_op = &hugetlbfs_dir_inode_operations; inode->i_fop = &simple_dir_operations; /* directory inodes start off with i_nlink == 2 (for "." entry) */ @@ -733,7 +730,6 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb, inode = new_inode(sb); if (inode) { - struct hugetlbfs_inode_info *info; inode->i_ino = get_next_ino(); inode_init_owner(inode, dir, mode); lockdep_set_class(&inode->i_mapping->i_mmap_rwsem, @@ -741,15 +737,6 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb, inode->i_mapping->a_ops = &hugetlbfs_aops; inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); inode->i_mapping->private_data = resv_map; - info = HUGETLBFS_I(inode); - /* - * The policy is initialized here even if we are creating a - * private inode because initialization simply creates an - * an empty rb tree and calls rwlock_init(), later when we - * call mpol_free_shared_policy() it will just return because - * the rb tree will still be empty. - */ - mpol_shared_policy_init(&info->policy, NULL); switch (mode & S_IFMT) { default: init_special_inode(inode, mode, dev); @@ -937,6 +924,18 @@ static struct inode *hugetlbfs_alloc_inode(struct super_block *sb) hugetlbfs_inc_free_inodes(sbinfo); return NULL; } + + /* + * Any time after allocation, hugetlbfs_destroy_inode can be called + * for the inode. mpol_free_shared_policy is unconditionally called + * as part of hugetlbfs_destroy_inode. So, initialize policy here + * in case of a quick call to destroy. + * + * Note that the policy is initialized even if we are creating a + * private inode. This simplifies hugetlbfs_destroy_inode. + */ + mpol_shared_policy_init(&p->policy, NULL); + return &p->vfs_inode; } -- 2.7.4