diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-12 19:43:20 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-12 19:43:20 -0700 |
commit | 4ca6df134847a6349620b485a3e63f00fb3bfad8 (patch) | |
tree | bf3ccdc0eaa41a2b51f134ba32d3ba28c9578b92 /fs/proc | |
parent | edaf3825182958a1fd5e39708fcb6ea48eca2060 (diff) | |
parent | 2fd1d2c4ceb2248a727696962cf3370dc9f5a0a4 (diff) |
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
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/internal.h | 2 | ||||
-rw-r--r-- | fs/proc/proc_sysctl.c | 43 |
2 files changed, 31 insertions, 14 deletions
diff --git a/fs/proc/internal.h b/fs/proc/internal.h index c5ae09b6c726..18694598bebf 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -67,7 +67,7 @@ struct proc_inode { struct proc_dir_entry *pde; struct ctl_table_header *sysctl; struct ctl_table *sysctl_entry; - struct list_head sysctl_inodes; + struct hlist_node sysctl_inodes; const struct proc_ns_operations *ns_ops; struct inode vfs_inode; }; diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 67985a7233c2..9bf06e2b1284 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -191,7 +191,7 @@ static void init_header(struct ctl_table_header *head, head->set = set; head->parent = NULL; head->node = node; - INIT_LIST_HEAD(&head->inodes); + INIT_HLIST_HEAD(&head->inodes); if (node) { struct ctl_table *entry; for (entry = table; entry->procname; entry++, node++) @@ -261,25 +261,42 @@ static void unuse_table(struct ctl_table_header *p) complete(p->unregistering); } -/* called under sysctl_lock */ static void proc_sys_prune_dcache(struct ctl_table_header *head) { - struct inode *inode, *prev = NULL; + struct inode *inode; struct proc_inode *ei; + struct hlist_node *node; + struct super_block *sb; rcu_read_lock(); - list_for_each_entry_rcu(ei, &head->inodes, sysctl_inodes) { - inode = igrab(&ei->vfs_inode); - if (inode) { - rcu_read_unlock(); - iput(prev); - prev = inode; - d_prune_aliases(inode); + for (;;) { + node = hlist_first_rcu(&head->inodes); + if (!node) + break; + ei = hlist_entry(node, struct proc_inode, sysctl_inodes); + spin_lock(&sysctl_lock); + hlist_del_init_rcu(&ei->sysctl_inodes); + spin_unlock(&sysctl_lock); + + inode = &ei->vfs_inode; + sb = inode->i_sb; + if (!atomic_inc_not_zero(&sb->s_active)) + continue; + inode = igrab(inode); + rcu_read_unlock(); + if (unlikely(!inode)) { + deactivate_super(sb); rcu_read_lock(); + continue; } + + d_prune_aliases(inode); + iput(inode); + deactivate_super(sb); + + rcu_read_lock(); } rcu_read_unlock(); - iput(prev); } /* called under sysctl_lock, will reacquire if has to wait */ @@ -461,7 +478,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb, } ei->sysctl = head; ei->sysctl_entry = table; - list_add_rcu(&ei->sysctl_inodes, &head->inodes); + hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes); head->count++; spin_unlock(&sysctl_lock); @@ -489,7 +506,7 @@ out: void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head) { spin_lock(&sysctl_lock); - list_del_rcu(&PROC_I(inode)->sysctl_inodes); + hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes); if (!--head->count) kfree_rcu(head, rcu); spin_unlock(&sysctl_lock); |