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binderfs: rework superblock destruction

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So far we relied on
.put_super = binderfs_put_super()
to destroy info we stashed in sb->s_fs_info. This gave us the required ordering
between ->evict_inode() and sb->s_fs_info destruction.

But the current implementation of binderfs_fill_super() has a memory leak in
the rare circumstance that d_make_root() fails because ->put_super() is only
called when sb->s_root is initialized. Fix this by removing ->put_super() and
simply do all that work in binderfs_kill_super().

Reported-by: Dongliang Mu <mudongliangabcd@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Link: https://lore.kernel.org/r/20220823095339.853371-1-brauner@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Al Viro 2022-08-23 11:53:39 +02:00 • committed by Greg Kroah-Hartman
parent eaf271ea84
commit 9d64d2405f
1 changed files with 17 additions and 13 deletions
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30
drivers/android/binderfs.c
View file

@ -339,22 +339,10 @@ static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
return 0;
}
static void binderfs_put_super(struct super_block *sb)
{
struct binderfs_info *info = sb->s_fs_info;
if (info && info->ipc_ns)
put_ipc_ns(info->ipc_ns);
kfree(info);
sb->s_fs_info = NULL;
}
static const struct super_operations binderfs_super_ops = {
.evict_inode = binderfs_evict_inode,
.show_options = binderfs_show_options,
.statfs = simple_statfs,
.put_super = binderfs_put_super,
};
static inline bool is_binderfs_control_device(const struct dentry *dentry)
@ -784,11 +772,27 @@ static int binderfs_init_fs_context(struct fs_context *fc)
return 0;
}
static void binderfs_kill_super(struct super_block *sb)
{
struct binderfs_info *info = sb->s_fs_info;
/*
* During inode eviction struct binderfs_info is needed.
* So first wipe the super_block then free struct binderfs_info.
*/
kill_litter_super(sb);
if (info && info->ipc_ns)
put_ipc_ns(info->ipc_ns);
kfree(info);
}
static struct file_system_type binder_fs_type = {
.name = "binder",
.init_fs_context = binderfs_init_fs_context,
.parameters = binderfs_fs_parameters,
.kill_sb = kill_litter_super,
.kill_sb = binderfs_kill_super,
.fs_flags = FS_USERNS_MOUNT,
};