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pipe: Check for ring full inside of the spinlock in pipe_write()

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Make pipe_write() check to see if the ring has become full between it
taking the pipe mutex, checking the ring status and then taking the
spinlock.

This can happen if a notification is written into the pipe as that happens
without the pipe mutex.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2019-10-07 16:30:51 +01:00
parent 7e25a73f1a
commit 8df441294d
1 changed files with 5 additions and 0 deletions
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5
fs/pipe.c
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@ -463,6 +463,11 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
spin_lock_irq(&pipe->wait.lock); spin_lock_irq(&pipe->wait.lock);
head = pipe->head; head = pipe->head;
if (pipe_full(head, pipe->tail, max_usage)) {
spin_unlock_irq(&pipe->wait.lock);
continue;
}
pipe->head = head + 1; pipe->head = head + 1;
/* Always wake up, even if the copy fails. Otherwise /* Always wake up, even if the copy fails. Otherwise