diff options
| author | Alexey Dobriyan <adobriyan@openvz.org> | 2007-05-08 00:25:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-08 11:15:01 -0700 |
| commit | 7695650a924a6859910c8c19dfa43b4d08224d66 (patch) | |
| tree | 5947c3e1b24600b6440468c11b30feeef31eee2c | |
| parent | 79c0b2df79eb56fc71e54c75cd7fb3acf84370f9 (diff) | |
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 <adobriyan@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/proc/generic.c | 2 | ||||
| -rw-r--r-- | fs/proc/inode.c | 12 | ||||
| -rw-r--r-- | include/linux/proc_fs.h | 3 |
3 files changed, 9 insertions, 8 deletions
diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 775fb21294d..22a08ff3475 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -398,6 +398,7 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { unsigned int ino = de->low_ino; + de_get(de); spin_unlock(&proc_subdir_lock); error = -EINVAL; inode = proc_get_inode(dir->i_sb, ino, de); @@ -414,6 +415,7 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam d_add(dentry, inode); return NULL; } + de_put(de); return ERR_PTR(error); } 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"); diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index f4f7a63cae1..3469f96bc8b 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -106,6 +106,9 @@ int task_statm(struct mm_struct *, int *, int *, int *, int *); char *task_mem(struct mm_struct *, char *); void clear_refs_smap(struct mm_struct *mm); +struct proc_dir_entry *de_get(struct proc_dir_entry *de); +void de_put(struct proc_dir_entry *de); + extern struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode, struct proc_dir_entry *parent); extern void remove_proc_entry(const char *name, struct proc_dir_entry *parent); |