Commit fc371912 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Linus Torvalds

userns: use refcount_t for reference counting instead atomic_t

refcount_t type and corresponding API should be used instead of atomic_t
wh en the variable is used as a reference counter.  This avoids accidental
refcounter overflows that might lead to use-after-free situations.

Link: http://lkml.kernel.org/r/20180703200141.28415-6-bigeasy@linutronix.deSigned-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 060288a7
......@@ -4,6 +4,7 @@
#include <linux/uidgid.h>
#include <linux/atomic.h>
#include <linux/refcount.h>
#include <linux/ratelimit.h>
struct key;
......@@ -12,7 +13,7 @@ struct key;
* Some day this will be a full-fledged user tracking system..
*/
struct user_struct {
atomic_t __count; /* reference count */
refcount_t __count; /* reference count */
atomic_t processes; /* How many processes does this user have? */
atomic_t sigpending; /* How many pending signals does this user have? */
#ifdef CONFIG_FANOTIFY
......@@ -59,7 +60,7 @@ extern struct user_struct root_user;
extern struct user_struct * alloc_uid(kuid_t);
static inline struct user_struct *get_uid(struct user_struct *u)
{
atomic_inc(&u->__count);
refcount_inc(&u->__count);
return u;
}
extern void free_uid(struct user_struct *);
......
......@@ -96,7 +96,7 @@ static DEFINE_SPINLOCK(uidhash_lock);
/* root_user.__count is 1, for init task cred */
struct user_struct root_user = {
.__count = ATOMIC_INIT(1),
.__count = REFCOUNT_INIT(1),
.processes = ATOMIC_INIT(1),
.sigpending = ATOMIC_INIT(0),
.locked_shm = 0,
......@@ -123,7 +123,7 @@ static struct user_struct *uid_hash_find(kuid_t uid, struct hlist_head *hashent)
hlist_for_each_entry(user, hashent, uidhash_node) {
if (uid_eq(user->uid, uid)) {
atomic_inc(&user->__count);
refcount_inc(&user->__count);
return user;
}
}
......@@ -170,7 +170,7 @@ void free_uid(struct user_struct *up)
return;
local_irq_save(flags);
if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
if (refcount_dec_and_lock(&up->__count, &uidhash_lock))
free_user(up, flags);
else
local_irq_restore(flags);
......@@ -191,7 +191,7 @@ struct user_struct *alloc_uid(kuid_t uid)
goto out_unlock;
new->uid = uid;
atomic_set(&new->__count, 1);
refcount_set(&new->__count, 1);
ratelimit_state_init(&new->ratelimit, HZ, 100);
ratelimit_set_flags(&new->ratelimit, RATELIMIT_MSG_ON_RELEASE);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment