[PATCH] timerfd/eventfd context lock doesn't protect against poll_wait

[Davi Arnaut]

Hi,

poll_wait() callback may modify the waitqueue without holding the
context private lock.

Signed-off-by: Davi E. M. Arnaut <[EMAIL PROTECTED]>

diff --git a/fs/eventfd.c b/fs/eventfd.c
index 480e2b3..9c672be 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -50,7 +50,7 @@ int eventfd_signal(struct file *file, int n)
                n = (int) (ULLONG_MAX - ctx->count);
        ctx->count += n;
        if (waitqueue_active(&ctx->wqh))
-               wake_up_locked(&ctx->wqh);
+               wake_up(&ctx->wqh);
        spin_unlock_irqrestore(&ctx->lock, flags);
 
        return n;
@@ -98,7 +98,7 @@ static ssize_t eventfd_read(struct file *file, char __user 
*buf, size_t count,
        if (ucnt > 0)
                res = sizeof(ucnt);
        else if (!(file->f_flags & O_NONBLOCK)) {
-               __add_wait_queue(&ctx->wqh, &wait);
+               add_wait_queue(&ctx->wqh, &wait);
                for (res = 0;;) {
                        set_current_state(TASK_INTERRUPTIBLE);
                        if (ctx->count > 0) {
@@ -114,13 +114,13 @@ static ssize_t eventfd_read(struct file *file, char 
__user *buf, size_t count,
                        schedule();
                        spin_lock_irq(&ctx->lock);
                }
-               __remove_wait_queue(&ctx->wqh, &wait);
+               remove_wait_queue(&ctx->wqh, &wait);
                __set_current_state(TASK_RUNNING);
        }
        if (res > 0) {
                ctx->count = 0;
                if (waitqueue_active(&ctx->wqh))
-                       wake_up_locked(&ctx->wqh);
+                       wake_up(&ctx->wqh);
        }
        spin_unlock_irq(&ctx->lock);
        if (res > 0 && put_user(ucnt, (__u64 __user *) buf))
@@ -148,7 +148,7 @@ static ssize_t eventfd_write(struct file *file, const char 
__user *buf, size_t c
        if (ULLONG_MAX - ctx->count > ucnt)
                res = sizeof(ucnt);
        else if (!(file->f_flags & O_NONBLOCK)) {
-               __add_wait_queue(&ctx->wqh, &wait);
+               add_wait_queue(&ctx->wqh, &wait);
                for (res = 0;;) {
                        set_current_state(TASK_INTERRUPTIBLE);
                        if (ULLONG_MAX - ctx->count > ucnt) {
@@ -163,13 +163,13 @@ static ssize_t eventfd_write(struct file *file, const 
char __user *buf, size_t c
                        schedule();
                        spin_lock_irq(&ctx->lock);
                }
-               __remove_wait_queue(&ctx->wqh, &wait);
+               remove_wait_queue(&ctx->wqh, &wait);
                __set_current_state(TASK_RUNNING);
        }
        if (res > 0) {
                ctx->count += ucnt;
                if (waitqueue_active(&ctx->wqh))
-                       wake_up_locked(&ctx->wqh);
+                       wake_up(&ctx->wqh);
        }
        spin_unlock_irq(&ctx->lock);
 
diff --git a/fs/timerfd.c b/fs/timerfd.c
index e329e37..e48eae7 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -41,8 +41,8 @@ static enum hrtimer_restart timerfd_tmrproc(struct hrtimer 
*htmr)
 
        spin_lock_irqsave(&ctx->lock, flags);
        ctx->expired = 1;
-       wake_up_locked(&ctx->wqh);
        spin_unlock_irqrestore(&ctx->lock, flags);
+       wake_up(&ctx->wqh);
 
        return HRTIMER_NORESTART;
 }
@@ -104,7 +104,7 @@ static ssize_t timerfd_read(struct file *file, char __user 
*buf, size_t count,
        spin_lock_irq(&ctx->lock);
        res = -EAGAIN;
        if (!ctx->expired && !(file->f_flags & O_NONBLOCK)) {
-               __add_wait_queue(&ctx->wqh, &wait);
+               add_wait_queue(&ctx->wqh, &wait);
                for (res = 0;;) {
                        set_current_state(TASK_INTERRUPTIBLE);
                        if (ctx->expired) {
@@ -119,7 +119,7 @@ static ssize_t timerfd_read(struct file *file, char __user 
*buf, size_t count,
                        schedule();
                        spin_lock_irq(&ctx->lock);
                }
-               __remove_wait_queue(&ctx->wqh, &wait);
+               remove_wait_queue(&ctx->wqh, &wait);
                __set_current_state(TASK_RUNNING);
        }
        if (ctx->expired) {
-
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