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apparmorfs: fix use-after-free on symlink traversal

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symlink body shouldn't be freed without an RCU delay.  Switch apparmorfs
to ->destroy_inode() and use of call_rcu(); free both the inode and symlink
body in the callback.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2019-04-10 14:04:34 -04:00
parent 46c8744196
commit f51dcd0f62
1 changed files with 9 additions and 4 deletions
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13
security/apparmor/apparmorfs.c
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@ -123,17 +123,22 @@ static int aafs_show_path(struct seq_file *seq, struct dentry *dentry)
return 0;
}
static void aafs_evict_inode(struct inode *inode)
static void aafs_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 aafs_destroy_inode(struct inode *inode)
{
call_rcu(&inode->i_rcu, aafs_i_callback);
}
static const struct super_operations aafs_super_ops = {
.statfs = simple_statfs,
.evict_inode = aafs_evict_inode,
.destroy_inode = aafs_destroy_inode,
.show_path = aafs_show_path,
};