From 7695650a924a6859910c8c19dfa43b4d08224d66 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Tue, 8 May 2007 00:25:45 -0700 Subject: Fix race between proc_get_inode() and remove_proc_entry() proc_lookup remove_proc_entry =========== ================= lock_kernel(); spin_lock(&proc_subdir_lock); [find PDE with refcount 0] spin_unlock(&proc_subdir_lock); spin_lock(&proc_subdir_lock); [find PDE with refcount 0] [check refcount and free PDE] spin_unlock(&proc_subdir_lock); proc_get_inode: de_get(de); /* boom */ Signed-off-by: Alexey Dobriyan Cc: "Eric W. Biederman" Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/inode.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) (limited to 'fs/proc/inode.c') diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 22b1158389a..d1de6378930 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -21,7 +21,7 @@ #include "internal.h" -static inline struct proc_dir_entry * de_get(struct proc_dir_entry *de) +struct proc_dir_entry *de_get(struct proc_dir_entry *de) { if (de) atomic_inc(&de->count); @@ -31,7 +31,7 @@ static inline struct proc_dir_entry * de_get(struct proc_dir_entry *de) /* * Decrements the use count and checks for deferred deletion. */ -static void de_put(struct proc_dir_entry *de) +void de_put(struct proc_dir_entry *de) { if (de) { lock_kernel(); @@ -146,11 +146,6 @@ struct inode *proc_get_inode(struct super_block *sb, unsigned int ino, { struct inode * inode; - /* - * Increment the use count so the dir entry can't disappear. - */ - de_get(de); - WARN_ON(de && de->deleted); if (de != NULL && !try_module_get(de->owner)) @@ -184,7 +179,6 @@ out_ino: if (de != NULL) module_put(de->owner); out_mod: - de_put(de); return NULL; } @@ -199,6 +193,7 @@ int proc_fill_super(struct super_block *s, void *data, int silent) s->s_op = &proc_sops; s->s_time_gran = 1; + de_get(&proc_root); root_inode = proc_get_inode(s, PROC_ROOT_INO, &proc_root); if (!root_inode) goto out_no_root; @@ -212,6 +207,7 @@ int proc_fill_super(struct super_block *s, void *data, int silent) out_no_root: printk("proc_read_super: get root inode failed\n"); iput(root_inode); + de_put(&proc_root); return -ENOMEM; } MODULE_LICENSE("GPL"); -- cgit v1.2.3