diff options
| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-10-02 11:18:59 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-02 16:57:25 +0200 |
| commit | 1a657f78dcc8ea7c53eaa1f2a45ea2315738c15f (patch) | |
| tree | a19972027792082fed505c8d540f7d877e37c0ab | |
| parent | [PATCH] proc: comment what proc_fill_cache does (diff) | |
| download | linux-1a657f78dcc8ea7c53eaa1f2a45ea2315738c15f.tar.xz linux-1a657f78dcc8ea7c53eaa1f2a45ea2315738c15f.zip | |
[PATCH] introduce get_task_pid() to fix unsafe get_pid()
proc_pid_make_inode:
ei->pid = get_pid(task_pid(task));
I think this is not safe. get_pid() can be preempted after checking "pid
!= NULL". Then the task exits, does detach_pid(), and RCU frees the pid.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | fs/proc/base.c | 4 | ||||
| -rw-r--r-- | include/linux/pid.h | 2 | ||||
| -rw-r--r-- | kernel/pid.c | 9 |
3 files changed, 13 insertions, 2 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index a317eb2c4442..82da55b5cffe 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -958,7 +958,7 @@ static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_st /* * grab the reference to task. */ - ei->pid = get_pid(task_pid(task)); + ei->pid = get_task_pid(task, PIDTYPE_PID); if (!ei->pid) goto out_unlock; @@ -1677,7 +1677,7 @@ static struct dentry *proc_base_instantiate(struct inode *dir, /* * grab the reference to the task. */ - ei->pid = get_pid(task_pid(task)); + ei->pid = get_task_pid(task, PIDTYPE_PID); if (!ei->pid) goto out_iput; diff --git a/include/linux/pid.h b/include/linux/pid.h index 7e39767b4c60..17b9e04d3586 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -68,6 +68,8 @@ extern struct task_struct *FASTCALL(pid_task(struct pid *pid, enum pid_type)); extern struct task_struct *FASTCALL(get_pid_task(struct pid *pid, enum pid_type)); +extern struct pid *get_task_pid(struct task_struct *task, enum pid_type type); + /* * attach_pid() and detach_pid() must be called with the tasklist_lock * write-held. diff --git a/kernel/pid.c b/kernel/pid.c index e4779bbb2058..b914392085f9 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -304,6 +304,15 @@ struct task_struct *find_task_by_pid_type(int type, int nr) EXPORT_SYMBOL(find_task_by_pid_type); +struct pid *get_task_pid(struct task_struct *task, enum pid_type type) +{ + struct pid *pid; + rcu_read_lock(); + pid = get_pid(task->pids[type].pid); + rcu_read_unlock(); + return pid; +} + struct task_struct *fastcall get_pid_task(struct pid *pid, enum pid_type type) { struct task_struct *result; |