pstore: Protect unlink with read_mutex

When update_ms is set, pstore_get_records() will be called when there's a new entry. But unlink can be called at the same time and might contend with the open-read-close loop. Depending on the implementation of platform driver, it may be safe or not. But I think it'd be better to protect those race in the first place. Cc: Stefan Hajnoczi <[email protected]> Signed-off-by: Namhyung Kim <[email protected]> Signed-off-by: Kees Cook <[email protected]>
josf · Nov 16, 2016 · e9e360b · e9e360b
1 parent 7a0032f
commit e9e360b
Showing 1 changed file with 5 additions and 2 deletions.
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
@@ -199,11 +199,14 @@ static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 	if (err)
 		return err;
 
-	if (p->psi->erase)
+	if (p->psi->erase) {
+		mutex_lock(&p->psi->read_mutex);
 		p->psi->erase(p->type, p->id, p->count,
 			      d_inode(dentry)->i_ctime, p->psi);
-	else
+		mutex_unlock(&p->psi->read_mutex);
+	} else {
 		return -EPERM;
+	}
 
 	return simple_unlink(dir, dentry);
 }