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authorAl Viro <viro@zeniv.linux.org.uk>2019-03-26 01:43:37 +0000
committerAl Viro <viro@zeniv.linux.org.uk>2019-04-01 00:31:02 -0400
commit93b919da64c15b90953f96a536e5e61df896ca57 (patch)
tree61aa43c048da6f2f480bd999cd9835cf3ef47d9d /fs
parent0cdc17ebd2072b6cdd3ec3695ea7ede745664a8b (diff)
downloadlinux-stericsson-93b919da64c15b90953f96a536e5e61df896ca57.tar.gz
debugfs: fix use-after-free on symlink traversal
symlink body shouldn't be freed without an RCU delay. Switch debugfs to ->destroy_inode() and use of call_rcu(); free both the inode and symlink body in the callback. Similar to solution for bpf, only here it's even more obvious that ->evict_inode() can be dropped. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/debugfs/inode.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 95b5e78c22b1..f25daa207421 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -163,19 +163,24 @@ static int debugfs_show_options(struct seq_file *m, struct dentry *root)
return 0;
}
-static void debugfs_evict_inode(struct inode *inode)
+static void debugfs_i_callback(struct rcu_head *head)
{
- truncate_inode_pages_final(&inode->i_data);
- clear_inode(inode);
+ struct inode *inode = container_of(head, struct inode, i_rcu);
if (S_ISLNK(inode->i_mode))
kfree(inode->i_link);
+ free_inode_nonrcu(inode);
+}
+
+static void debugfs_destroy_inode(struct inode *inode)
+{
+ call_rcu(&inode->i_rcu, debugfs_i_callback);
}
static const struct super_operations debugfs_super_operations = {
.statfs = simple_statfs,
.remount_fs = debugfs_remount,
.show_options = debugfs_show_options,
- .evict_inode = debugfs_evict_inode,
+ .destroy_inode = debugfs_destroy_inode,
};
static void debugfs_release_dentry(struct dentry *dentry)