Commit ab04de8e authored Sep 07, 2020 by Christoph Hellwig Committed by Greg Kroah-Hartman Sep 07, 2020

/dev/zero: fixups for ->read



Reported the cleared bytes in case of a partial clear_user instead
of -EFAULT, and remove a pointless conditional, as cleared must be
non-zero by the time we hit the signal_pending check.

Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20200907082700.2057137-1-hch@lst.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 947bece1

drivers/char/mem.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -733,14 +733,20 @@ static ssize_t read_zero(struct file file, char __user buf,

		while (count) {
		size_t chunk = min_t(size_t, count, PAGE_SIZE);
		size_t left;

		if (clear_user(buf + cleared, chunk))
		return cleared ? cleared : -EFAULT;
		left = clear_user(buf + cleared, chunk);
		if (unlikely(left)) {
		cleared += (chunk - left);
		if (!cleared)
		return -EFAULT;
		break;
		}
		cleared += chunk;
		count -= chunk;

		if (signal_pending(current))
		return cleared ? cleared : -ERESTARTSYS;
		break;
		cond_resched();
		}

Admin message