diff options
Diffstat (limited to 'kernel/futex')
| -rw-r--r-- | kernel/futex/core.c | 16 | ||||
| -rw-r--r-- | kernel/futex/requeue.c | 6 | ||||
| -rw-r--r-- | kernel/futex/syscalls.c | 106 |
3 files changed, 72 insertions, 56 deletions
diff --git a/kernel/futex/core.c b/kernel/futex/core.c index d9bb5567af0c..125804fbb5cb 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -1722,12 +1722,9 @@ int futex_mm_init(struct mm_struct *mm) RCU_INIT_POINTER(mm->futex_phash, NULL); mm->futex_phash_new = NULL; /* futex-ref */ + mm->futex_ref = NULL; atomic_long_set(&mm->futex_atomic, 0); mm->futex_batches = get_state_synchronize_rcu(); - mm->futex_ref = alloc_percpu(unsigned int); - if (!mm->futex_ref) - return -ENOMEM; - this_cpu_inc(*mm->futex_ref); /* 0 -> 1 */ return 0; } @@ -1801,6 +1798,17 @@ static int futex_hash_allocate(unsigned int hash_slots, unsigned int flags) } } + if (!mm->futex_ref) { + /* + * This will always be allocated by the first thread and + * therefore requires no locking. + */ + mm->futex_ref = alloc_percpu(unsigned int); + if (!mm->futex_ref) + return -ENOMEM; + this_cpu_inc(*mm->futex_ref); /* 0 -> 1 */ + } + fph = kvzalloc(struct_size(fph, queues, hash_slots), GFP_KERNEL_ACCOUNT | __GFP_NOWARN); if (!fph) diff --git a/kernel/futex/requeue.c b/kernel/futex/requeue.c index c716a66f8692..d818b4d47f1b 100644 --- a/kernel/futex/requeue.c +++ b/kernel/futex/requeue.c @@ -230,8 +230,9 @@ static inline void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key, struct futex_hash_bucket *hb) { - q->key = *key; + struct task_struct *task; + q->key = *key; __futex_unqueue(q); WARN_ON(!q->rt_waiter); @@ -243,10 +244,11 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key, futex_hash_get(hb); q->drop_hb_ref = true; q->lock_ptr = &hb->lock; + task = READ_ONCE(q->task); /* Signal locked state to the waiter */ futex_requeue_pi_complete(q, 1); - wake_up_state(q->task, TASK_NORMAL); + wake_up_state(task, TASK_NORMAL); } /** diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 4b6da9116aa6..880c9bf2f315 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -39,6 +39,56 @@ SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, return 0; } +static inline void __user *futex_task_robust_list(struct task_struct *p, bool compat) +{ +#ifdef CONFIG_COMPAT + if (compat) + return p->compat_robust_list; +#endif + return p->robust_list; +} + +static void __user *futex_get_robust_list_common(int pid, bool compat) +{ + struct task_struct *p = current; + void __user *head; + int ret; + + scoped_guard(rcu) { + if (pid) { + p = find_task_by_vpid(pid); + if (!p) + return (void __user *)ERR_PTR(-ESRCH); + } + get_task_struct(p); + } + + /* + * Hold exec_update_lock to serialize with concurrent exec() + * so ptrace_may_access() is checked against stable credentials + */ + ret = down_read_killable(&p->signal->exec_update_lock); + if (ret) + goto err_put; + + ret = -EPERM; + if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) + goto err_unlock; + + head = futex_task_robust_list(p, compat); + + up_read(&p->signal->exec_update_lock); + put_task_struct(p); + + return head; + +err_unlock: + up_read(&p->signal->exec_update_lock); +err_put: + put_task_struct(p); + return (void __user *)ERR_PTR(ret); +} + /** * sys_get_robust_list() - Get the robust-futex list head of a task * @pid: pid of the process [zero for current task] @@ -49,36 +99,14 @@ SYSCALL_DEFINE3(get_robust_list, int, pid, struct robust_list_head __user * __user *, head_ptr, size_t __user *, len_ptr) { - struct robust_list_head __user *head; - unsigned long ret; - struct task_struct *p; - - rcu_read_lock(); - - ret = -ESRCH; - if (!pid) - p = current; - else { - p = find_task_by_vpid(pid); - if (!p) - goto err_unlock; - } - - ret = -EPERM; - if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) - goto err_unlock; + struct robust_list_head __user *head = futex_get_robust_list_common(pid, false); - head = p->robust_list; - rcu_read_unlock(); + if (IS_ERR(head)) + return PTR_ERR(head); if (put_user(sizeof(*head), len_ptr)) return -EFAULT; return put_user(head, head_ptr); - -err_unlock: - rcu_read_unlock(); - - return ret; } long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, @@ -455,36 +483,14 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid, compat_uptr_t __user *, head_ptr, compat_size_t __user *, len_ptr) { - struct compat_robust_list_head __user *head; - unsigned long ret; - struct task_struct *p; - - rcu_read_lock(); - - ret = -ESRCH; - if (!pid) - p = current; - else { - p = find_task_by_vpid(pid); - if (!p) - goto err_unlock; - } - - ret = -EPERM; - if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS)) - goto err_unlock; + struct compat_robust_list_head __user *head = futex_get_robust_list_common(pid, true); - head = p->compat_robust_list; - rcu_read_unlock(); + if (IS_ERR(head)) + return PTR_ERR(head); if (put_user(sizeof(*head), len_ptr)) return -EFAULT; return put_user(ptr_to_compat(head), head_ptr); - -err_unlock: - rcu_read_unlock(); - - return ret; } #endif /* CONFIG_COMPAT */ |