[PATCH v2] ocfs2: Pin owning modules for open debugfs files

[Cen Zhang <zzzccc427@gmail.com>]

The OCFS2 debugfs file operation tables do not set owner. The
full debugfs proxy obtains real_fops with fops_get() at open and
keeps it until final release. Without an owner, this does not acquire
a reference to the module containing the table and its callbacks.
Removing the debugfs entries does not drain retained open files.

An open connected_nodes file can therefore outlive ocfs2_nodemanager
and make full_proxy_release() read real_fops->release from freed
module memory. Heming also reproduced the issue with fs_state and
asked for the other OCFS2 debugfs operation tables to be checked.

Set owner to THIS_MODULE in all eleven explicit debugfs operation
tables: five in ocfs2_nodemanager, four in ocfs2_dlm, and two in
ocfs2. The existing debugfs get/put pair then holds the appropriate
module until final release. Leave the open, read and release callbacks
unchanged. The blockcheck table already sets owner through
DEFINE_DEBUGFS_ATTRIBUTE(), so it needs no change.

The original controlled test used an unloadable OCFS2 module and
case-local probe filters without changing the candidate open, unload
or release logic. Closing a retained connected_nodes file after
normal unload produced:

  BUG: unable to handle page fault for address: fffffbfff804cfef
  Oops: Oops: 0000 [#1] SMP KASAN NOPTI
  RIP: 0010:full_proxy_release+0xbf/0x190
  Call Trace:
   <TASK>
   __fput+0x39a/0xa60
   fput_close_sync+0xff/0x200
   __x64_sys_close+0x8c/0xf0
   do_syscall_64+0x114/0x620
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
   </TASK>
  Modules linked in: [last unloaded: ocfs2_nodemanager]

Fixes: 2309e9e040fe ("ocfs2/net: Add debug interface to o2net")
Fixes: 87d3d3f3931f ("ocfs2/hb: Expose the list of heartbeating nodes via debugfs")
Fixes: 3ba169ccec1c ("ocfs2/cluster: Add new function o2net_fill_node_map()")
Fixes: 50397507e856 ("ocfs2: Expose the file system state via debugfs")
Fixes: ccd979bdbce9 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem")
Fixes: 7209300a9b98 ("ocfs2/dlm: Dumps the purgelist into a debugfs file")
Fixes: d0129aceaecc ("ocfs2/dlm: Dumps the mles into a debugfs file")
Fixes: 4e3d24ed1a12 ("ocfs2/dlm: Dumps the lockres' into a debugfs file")
Fixes: 007dce53a29c ("ocfs2/dlm: Dump the dlm state in a debugfs file")
Assisted-by: LLM
Cc: <stable@vger.kernel.org>
Suggested-by: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: Cen Zhang <zzzccc427@gmail.com>

---
Changes in v2:
- Cover fs_state and locking_state in the OCFS2 filesystem module.
- Cover all four OCFS2 DLM debugfs operation tables.
- Keep the five node manager fixes and the original diagnostic.
- Add explicit module headers and Fixes tags for the added tables.
- Add Cc: stable@vger.kernel.org.

Link to v1: https://lore.kernel.org/r/pm-ocfs2-objects-candidate-0089-v2-4c67f48d4e2d0fc85990@gmail.com

 fs/ocfs2/cluster/heartbeat.c | 1 +
 fs/ocfs2/cluster/netdebug.c  | 4 ++++
 fs/ocfs2/dlm/dlmdebug.c      | 5 +++++
 fs/ocfs2/dlmglue.c           | 2 ++
 fs/ocfs2/super.c             | 1 +
 5 files changed, 13 insertions(+)

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 8e6ead433228e7419bfbbe5c7cdde65c654a24f4..1d4f71190d27b2b7fcf7db7b39fefcad5cc669cc 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -1447,6 +1447,7 @@ static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
 #endif  /* CONFIG_DEBUG_FS */
 
 static const struct file_operations o2hb_debug_fops = {
+	.owner = THIS_MODULE,
 	.open =		o2hb_debug_open,
 	.release =	o2hb_debug_release,
 	.read =		o2hb_debug_read,
diff --git a/fs/ocfs2/cluster/netdebug.c b/fs/ocfs2/cluster/netdebug.c
index f7ab66e70799302f3ed4e70ab6a8fb057dd0bfa9..9b8e2cdd05ed452f98f95d45bfb7f5865db434f7 100644
--- a/fs/ocfs2/cluster/netdebug.c
+++ b/fs/ocfs2/cluster/netdebug.c
@@ -183,6 +183,7 @@ static int nst_fop_release(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations nst_seq_fops = {
+	.owner = THIS_MODULE,
 	.open = nst_fop_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
@@ -415,6 +416,7 @@ static int stats_fop_open(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations stats_seq_fops = {
+	.owner = THIS_MODULE,
 	.open = stats_fop_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
@@ -427,6 +429,7 @@ static int sc_fop_open(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations sc_seq_fops = {
+	.owner = THIS_MODULE,
 	.open = sc_fop_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
@@ -476,6 +479,7 @@ static ssize_t o2net_debug_read(struct file *file, char __user *buf,
 }
 
 static const struct file_operations nodes_fops = {
+	.owner = THIS_MODULE,
 	.open		= nodes_fop_open,
 	.release	= o2net_debug_release,
 	.read		= o2net_debug_read,
diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c
index ce6d301cb9420385211d20d59637069154a89993..4face0bea236748b679571e6ade068658d33bd12 100644
--- a/fs/ocfs2/dlm/dlmdebug.c
+++ b/fs/ocfs2/dlm/dlmdebug.c
@@ -7,6 +7,7 @@
  * Copyright (C) 2004, 2008 Oracle.  All rights reserved.
  */
 
+#include <linux/module.h>
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/highmem.h>
@@ -339,6 +340,7 @@ static int debug_purgelist_open(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations debug_purgelist_fops = {
+	.owner = THIS_MODULE,
 	.open =		debug_purgelist_open,
 	.release =	debug_release,
 	.read =		debug_read,
@@ -394,6 +396,7 @@ static int debug_mle_open(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations debug_mle_fops = {
+	.owner = THIS_MODULE,
 	.open =		debug_mle_open,
 	.release =	debug_release,
 	.read =		debug_read,
@@ -601,6 +604,7 @@ static int debug_lockres_release(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations debug_lockres_fops = {
+	.owner = THIS_MODULE,
 	.open =		debug_lockres_open,
 	.release =	debug_lockres_release,
 	.read =		seq_read,
@@ -791,6 +795,7 @@ static int debug_state_open(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations debug_state_fops = {
+	.owner = THIS_MODULE,
 	.open =		debug_state_open,
 	.release =	debug_release,
 	.read =		debug_read,
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 6bc4a21cf5f02f04a6b54100925084aed239ae62..b332938fe57f87c3d9a81e3800eed1a25e49de1b 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -7,6 +7,7 @@
  * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
  */
 
+#include <linux/module.h>
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/highmem.h>
@@ -3332,6 +3333,7 @@ static int ocfs2_dlm_debug_open(struct inode *inode, struct file *file)
 }
 
 static const struct file_operations ocfs2_dlm_debug_fops = {
+	.owner = THIS_MODULE,
 	.open =		ocfs2_dlm_debug_open,
 	.release =	ocfs2_dlm_debug_release,
 	.read =		seq_read,
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 1e76b1d9fe0af4b3cf503e91e1dd077762fef88a..1f6d828a470fb28ccde2e6ed9a82a4ed7c294201 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -387,6 +387,7 @@ static ssize_t ocfs2_debug_read(struct file *file, char __user *buf,
 #endif	/* CONFIG_DEBUG_FS */
 
 static const struct file_operations ocfs2_osb_debug_fops = {
+	.owner = THIS_MODULE,
 	.open =		ocfs2_osb_debug_open,
 	.release =	ocfs2_debug_release,
 	.read =		ocfs2_debug_read,