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pstore: Remove filesystem records when backend is unregistered

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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: Luis 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: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2020-05-04 19:46:53 -07:00
parent 78c83c828c
commit 609e28bb13
3 changed files with 36 additions and 0 deletions
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32
fs/pstore/inode.c
View File

@ -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;

1
fs/pstore/internal.h
View File

@ -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,

3
fs/pstore/platform.c
View File

@ -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;