From b9d39d17e4819ca2e69ad1f14acaad12240a1de5 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 9 Jun 2017 08:50:49 -0700 Subject: [PATCH] device-dax: fix 'dax' device filesystem inode destruction crash The inode destruction path for the 'dax' device filesystem incorrectly assumes that the inode was initialized through 'alloc_dax()'. However, if someone attempts to directly mount the dax filesystem with 'mount -t dax dax mnt' that will bypass 'alloc_dax()' and the following failure signatures may occur as a result: kill_dax() must be called before final iput() WARNING: CPU: 2 PID: 1188 at drivers/dax/super.c:243 dax_destroy_inode+0x48/0x50 RIP: 0010:dax_destroy_inode+0x48/0x50 Call Trace: destroy_inode+0x3b/0x60 evict+0x139/0x1c0 iput+0x1f9/0x2d0 dentry_unlink_inode+0xc3/0x160 __dentry_kill+0xcf/0x180 ? dput+0x37/0x3b0 dput+0x3a3/0x3b0 do_one_tree+0x36/0x40 shrink_dcache_for_umount+0x2d/0x90 generic_shutdown_super+0x1f/0x120 kill_anon_super+0x12/0x20 deactivate_locked_super+0x43/0x70 deactivate_super+0x4e/0x60 general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC RIP: 0010:kfree+0x6d/0x290 Call Trace: dax_i_callback+0x22/0x60 ? dax_destroy_inode+0x50/0x50 rcu_process_callbacks+0x298/0x740 ida_remove called for id=0 which is not allocated. WARNING: CPU: 0 PID: 0 at lib/idr.c:383 ida_remove+0x110/0x120 [..] Call Trace: ida_simple_remove+0x2b/0x50 ? dax_destroy_inode+0x50/0x50 dax_i_callback+0x3c/0x60 rcu_process_callbacks+0x298/0x740 Add missing initialization of the 'struct dax_device' and inode so that the destruction path does not kfree() or ida_simple_remove() uninitialized data. Fixes: 7b6be8444e0f ("dax: refactor dax-fs into a generic provider of 'struct dax_device' instances") Reported-by: Sasha Levin Signed-off-by: Dan Williams --- drivers/dax/super.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 6ed32aac8bbe..922d0823f8ec 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -210,9 +210,12 @@ EXPORT_SYMBOL_GPL(kill_dax); static struct inode *dax_alloc_inode(struct super_block *sb) { struct dax_device *dax_dev; + struct inode *inode; dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL); - return &dax_dev->inode; + inode = &dax_dev->inode; + inode->i_rdev = 0; + return inode; } static struct dax_device *to_dax_dev(struct inode *inode) @@ -227,7 +230,8 @@ static void dax_i_callback(struct rcu_head *head) kfree(dax_dev->host); dax_dev->host = NULL; - ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev)); + if (inode->i_rdev) + ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev)); kmem_cache_free(dax_cache, dax_dev); } @@ -423,6 +427,7 @@ static void init_once(void *_dax_dev) struct dax_device *dax_dev = _dax_dev; struct inode *inode = &dax_dev->inode; + memset(dax_dev, 0, sizeof(*dax_dev)); inode_init_once(inode); } -- 2.20.1