wext: fix get_wireless_stats locking (7be69c0b) · Commits · 戴 / test

Currently, get_wireless_stats is racy by _design_. This is because it returns a buffer, which needs to be statically allocated since it cannot be freed if it was allocated dynamically. Also, SIOCGIWSTATS and /proc/net/wireless use no common lock, and /proc/net/wireless accesses are not synchronised against each other. This is a design flaw in get_wireless_stats since the beginning. This patch fixes it by wrapping /proc/net/wireless accesses with the RTNL so they are protected against each other and SIOCGIWSTATS. The more correct method of fixing this would be to pass in the buffer instead of returning it and have the caller take care of synchronisation of the buffer, but even then most drivers probably assume that their callback is protected by the RTNL like all other wext callbacks. Signed-off-by:

Johannes Berg <johannes@sipsolutions.net> Signed-off-by:

John W. Linville <linville@tuxdriver.com>

net/wireless/wext.c

+18 −4

Original line number	Diff line number	Diff line
		@@ -649,14 +649,28 @@ static int wireless_seq_show(struct seq_file seq, void v)
		return 0;
		}

		static void wireless_dev_seq_start(struct seq_file seq, loff_t *pos)
		__acquires(dev_base_lock)
		{
		rtnl_lock();
		return dev_seq_start(seq, pos);
		}

		static void wireless_dev_seq_stop(struct seq_file seq, void v)
		__releases(dev_base_lock)
		{
		dev_seq_stop(seq, v);
		rtnl_unlock();
		}

		static const struct seq_operations wireless_seq_ops = {
		.start = dev_seq_start,
		.start = wireless_dev_seq_start,
		.next = dev_seq_next,
		.stop = dev_seq_stop,
		.stop = wireless_dev_seq_stop,
		.show = wireless_seq_show,
		};

		static int wireless_seq_open(struct inode inode, struct file file)
		static int seq_open_wireless(struct inode inode, struct file file)
		{
		return seq_open_net(inode, file, &wireless_seq_ops,
		sizeof(struct seq_net_private));
		@@ -664,7 +678,7 @@ static int wireless_seq_open(struct inode inode, struct file file)

		static const struct file_operations wireless_seq_fops = {
		.owner = THIS_MODULE,
		.open = wireless_seq_open,
		.open = seq_open_wireless,
		.read = seq_read,
		.llseek = seq_lseek,
		.release = seq_release_net,

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