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| author | Al Viro <viro@zeniv.linux.org.uk> | 2019-03-26 01:43:37 +0000 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2019-04-01 00:31:02 -0400 |
| commit | 93b919da64c15b90953f96a536e5e61df896ca57 (patch) | |
| tree | 61aa43c048da6f2f480bd999cd9835cf3ef47d9d | |
| parent | 0cdc17ebd2072b6cdd3ec3695ea7ede745664a8b (diff) | |
| download | linux-93b919da64c15b90953f96a536e5e61df896ca57.tar.bz2 | |
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>
| -rw-r--r-- | fs/debugfs/inode.c | 13 |
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) |