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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull sysctl fix from Eric Biederman: "A rather embarassing and hard to hit bug was merged into 4.11-rc1. Andrei Vagin tracked this bug now and after some staring at the code I came up with a fix" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: proc: Fix proc_sys_prune_dcache to hold a sb reference
This commit is contained in:
commit
4ca6df1348
3 changed files with 32 additions and 15 deletions
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@ -67,7 +67,7 @@ struct proc_inode {
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struct proc_dir_entry *pde;
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struct ctl_table_header *sysctl;
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struct ctl_table *sysctl_entry;
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struct list_head sysctl_inodes;
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struct hlist_node sysctl_inodes;
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const struct proc_ns_operations *ns_ops;
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struct inode vfs_inode;
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};
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@ -191,7 +191,7 @@ static void init_header(struct ctl_table_header *head,
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head->set = set;
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head->parent = NULL;
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head->node = node;
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INIT_LIST_HEAD(&head->inodes);
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INIT_HLIST_HEAD(&head->inodes);
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if (node) {
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struct ctl_table *entry;
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for (entry = table; entry->procname; entry++, node++)
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@ -261,25 +261,42 @@ static void unuse_table(struct ctl_table_header *p)
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complete(p->unregistering);
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}
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/* called under sysctl_lock */
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static void proc_sys_prune_dcache(struct ctl_table_header *head)
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{
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struct inode *inode, *prev = NULL;
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struct inode *inode;
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struct proc_inode *ei;
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struct hlist_node *node;
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struct super_block *sb;
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rcu_read_lock();
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list_for_each_entry_rcu(ei, &head->inodes, sysctl_inodes) {
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inode = igrab(&ei->vfs_inode);
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if (inode) {
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rcu_read_unlock();
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iput(prev);
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prev = inode;
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d_prune_aliases(inode);
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for (;;) {
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node = hlist_first_rcu(&head->inodes);
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if (!node)
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break;
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ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
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spin_lock(&sysctl_lock);
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hlist_del_init_rcu(&ei->sysctl_inodes);
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spin_unlock(&sysctl_lock);
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inode = &ei->vfs_inode;
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sb = inode->i_sb;
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if (!atomic_inc_not_zero(&sb->s_active))
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continue;
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inode = igrab(inode);
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rcu_read_unlock();
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if (unlikely(!inode)) {
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deactivate_super(sb);
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rcu_read_lock();
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continue;
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}
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d_prune_aliases(inode);
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iput(inode);
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deactivate_super(sb);
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rcu_read_lock();
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}
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rcu_read_unlock();
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iput(prev);
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}
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/* called under sysctl_lock, will reacquire if has to wait */
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@ -461,7 +478,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
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}
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ei->sysctl = head;
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ei->sysctl_entry = table;
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list_add_rcu(&ei->sysctl_inodes, &head->inodes);
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hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
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head->count++;
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spin_unlock(&sysctl_lock);
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@ -489,7 +506,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
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void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
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{
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spin_lock(&sysctl_lock);
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list_del_rcu(&PROC_I(inode)->sysctl_inodes);
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hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
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if (!--head->count)
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kfree_rcu(head, rcu);
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spin_unlock(&sysctl_lock);
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@ -143,7 +143,7 @@ struct ctl_table_header
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struct ctl_table_set *set;
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struct ctl_dir *parent;
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struct ctl_node *node;
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struct list_head inodes; /* head for proc_inode->sysctl_inodes */
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struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
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};
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struct ctl_dir {
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