Commit 609e28bb authored by Kees Cook's avatar Kees Cook
Browse files

pstore: Remove filesystem records when backend is unregistered 



If a backend was unloaded without having first removed all its
associated records in pstorefs, subsequent removals would crash while
attempting to call into the now missing backend. Add automatic removal
from the tree in pstore_unregister(), so that no references to the
backend remain.

Reported-by: default avatarLuis Henriques <lhenriques@suse.com>
Link: https://lore.kernel.org/lkml/87o8yrmv69.fsf@suse.com
Link: https://lore.kernel.org/lkml/20200506152114.50375-11-keescook@chromium.org/


Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 78c83c82

fs/pstore/inode.c

+32 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ static struct super_block *pstore_sb; 


struct pstore_private {

	struct list_head list;

	struct dentry *dentry;

	struct pstore_record *record;

	size_t total_size;

};
@@ -191,6 +192,7 @@ static int pstore_unlink(struct inode *dir, struct dentry *dentry) 
		list_del_init(&p->list);

	else

		rc = -ENOENT;

	p->dentry = NULL;

	mutex_unlock(&records_list_lock);

	if (rc)

		return rc;
@@ -306,6 +308,35 @@ static struct dentry *psinfo_lock_root(void) 
	return root;

}



int pstore_put_backend_records(struct pstore_info *psi)

{

	struct pstore_private *pos, *tmp;

	struct dentry *root;

	int rc = 0;



	root = psinfo_lock_root();

	if (!root)

		return 0;



	mutex_lock(&records_list_lock);

	list_for_each_entry_safe(pos, tmp, &records_list, list) {

		if (pos->record->psi == psi) {

			list_del_init(&pos->list);

			rc = simple_unlink(d_inode(root), pos->dentry);

			if (WARN_ON(rc))

				break;

			d_drop(pos->dentry);

			dput(pos->dentry);

			pos->dentry = NULL;

		}

	}

	mutex_unlock(&records_list_lock);



	inode_unlock(d_inode(root));



	return rc;

}



/*

 * Make a regular file in the root directory of our file system.

 * Load it up with "size" bytes of data from "buf".
@@ -352,6 +383,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) 
	if (!dentry)

		goto fail_private;



	private->dentry = dentry;

	private->record = record;

	inode->i_size = private->total_size = size;

	inode->i_private = private;

fs/pstore/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ extern void pstore_set_kmsg_bytes(int); 
extern void	pstore_get_records(int);

extern void	pstore_get_backend_records(struct pstore_info *psi,

					   struct dentry *root, int quiet);

extern int	pstore_put_backend_records(struct pstore_info *psi);

extern int	pstore_mkfile(struct dentry *root,

			      struct pstore_record *record);

extern void	pstore_record_init(struct pstore_record *record,

fs/pstore/platform.c

+3 −0
Original line number Diff line number Diff line
@@ -657,6 +657,9 @@ void pstore_unregister(struct pstore_info *psi) 
	del_timer_sync(&pstore_timer);

	flush_work(&pstore_work);



	/* Remove all backend records from filesystem tree. */

	pstore_put_backend_records(psi);



	free_buf_for_compression();



	psinfo = NULL;

CRA Git | Maintained and supported by SUSTech CRA and CCSE