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Commit 3479e4d0 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Gerrit - the friendly Code Review server
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Use after free from pid_nr_ns() 



There is use after free reported due to group
leader task is already freed but other tasks are
still holding the group leader task address in
task->group_leader pointer.

pid_nr_ns+0x10/0x38
cgroup_pidlist_start+0x144/0x400
cgroup_seqfile_start+0x1c/0x24
kernfs_seq_start+0x54/0x90
seq_read+0x15c/0x3a8
kernfs_fop_read+0x38/0x160
__vfs_read+0x28/0xc8
vfs_read+0x84/0xfc

Change-Id: Ib6b3fc75bf0d24a04455bf81d54900c21c434958
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPrasad Sodagudi <psodagud@codeaurora.org>
parent 7d03daac

include/linux/pid.h

+3 −1
Original line number Diff line number Diff line
@@ -8,7 +8,9 @@ enum pid_type 
	PIDTYPE_PID,

	PIDTYPE_PGID,

	PIDTYPE_SID,

	PIDTYPE_MAX

	PIDTYPE_MAX,

	/* only valid to __task_pid_nr_ns() */

	__PIDTYPE_TGID

};



/*

include/linux/sched.h

+11 −8
Original line number Diff line number Diff line
@@ -2250,15 +2250,8 @@ static inline pid_t task_tgid_nr(struct task_struct *tsk) 
	return tsk->tgid;

}



pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);



static inline pid_t task_tgid_vnr(struct task_struct *tsk)

{

	return pid_vnr(task_tgid(tsk));

}





static inline int pid_alive(const struct task_struct *p);

static inline pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);

static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)

{

	pid_t pid = 0;
@@ -2299,6 +2292,16 @@ static inline pid_t task_session_vnr(struct task_struct *tsk) 
	return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);

}



static inline pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)

{

	return __task_pid_nr_ns(tsk, __PIDTYPE_TGID, ns);

}



static inline pid_t task_tgid_vnr(struct task_struct *tsk)

{

	return __task_pid_nr_ns(tsk, __PIDTYPE_TGID, NULL);

}



/* obsolete, do not use */

static inline pid_t task_pgrp_nr(struct task_struct *tsk)

{

kernel/pid.c

+4 −7
Original line number Diff line number Diff line
@@ -526,8 +526,11 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, 
	if (!ns)

		ns = task_active_pid_ns(current);

	if (likely(pid_alive(task))) {

		if (type != PIDTYPE_PID)

		if (type != PIDTYPE_PID) {

			if (type == __PIDTYPE_TGID)

				type = PIDTYPE_PID;

			task = task->group_leader;

		}

		nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns);

	}

	rcu_read_unlock();
@@ -536,12 +539,6 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, 
}

EXPORT_SYMBOL(__task_pid_nr_ns);



pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)

{

	return pid_nr_ns(task_tgid(tsk), ns);

}

EXPORT_SYMBOL(task_tgid_nr_ns);



struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)

{

	return ns_of_pid(task_pid(tsk));