Commit 1af95de6 authored Jun 23, 2015 by Wang YanQing Committed by Al Viro Jul 01, 2015

fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation



Execution of get_anon_bdev concurrently and preemptive kernel all
could bring race condition, it isn't enough to check dev against
its upper limitation with equality operator only.

This patch fix it.

Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 2adc376c

fs/super.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -842,7 +842,7 @@ int get_anon_bdev(dev_t *p)
		else if (error)
		return -EAGAIN;

		if (dev == (1 << MINORBITS)) {
		if (dev >= (1 << MINORBITS)) {
		spin_lock(&unnamed_dev_lock);
		ida_remove(&unnamed_dev_ida, dev);
		if (unnamed_dev_start > dev)