Patch "Bluetooth: vhci: purge unhandled skbs" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

Bluetooth: vhci: purge unhandled skbs

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
bluetooth-vhci-purge-unhandled-skbs.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jiri Slaby <[email protected]>
Date: Sat, 19 Mar 2016 11:49:43 +0100
Subject: Bluetooth: vhci: purge unhandled skbs

From: Jiri Slaby <[email protected]>

commit 13407376b255325fa817798800117a839f3aa055 upstream.

The write handler allocates skbs and queues them into data->readq. Read side should read them, if there is any. If there is none, skbs should be dropped by hdev->flush. But this happens only if the device is HCI_UP, i.e. hdev->power_on work was triggered already. When it was not, skbs stay allocated in the queue when /dev/vhci is closed. So purge the queue in ->release.

Program to reproduce:

	#include <err.h>
	#include <fcntl.h>
	#include <stdio.h>
	#include <unistd.h>

	#include <sys/stat.h>
	#include <sys/types.h>
	#include <sys/uio.h>

	int main()
	{
		char buf[] = { 0xff, 0 };
		struct iovec iov = {
			.iov_base = buf,
			.iov_len = sizeof(buf),
		};
		int fd;

		while (1) {
			fd = open("/dev/vhci", O_RDWR);
			if (fd < 0)
				err(1, "open");

			usleep(50);

			if (writev(fd, &iov, 1) < 0)
				err(1, "writev");

			usleep(50);

			close(fd);
		}

		return 0;
	}

Result:
kmemleak: 4609 new suspected memory leaks unreferenced object 0xffff88059f4d5440 (size 232):
comm "vhci", pid 1084, jiffies 4294912542 (age 37569.296s) hex dump (first 32 bytes):

    20 f0 23 87 05 88 ff ff 20 f0 23 87 05 88 ff ff   .#..... .#.....
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
...
    [<ffffffff81ece010>] __alloc_skb+0x0/0x5a0
    [<ffffffffa021886c>] vhci_create_device+0x5c/0x580 [hci_vhci]
    [<ffffffffa0219436>] vhci_write+0x306/0x4c8 [hci_vhci]

---
 drivers/bluetooth/hci_vhci.c |    1 +
 1 file changed, 1 insertion(+)

@@ -344,6 +344,7 @@ static int vhci_release(struct inode *in
 		hci_free_dev(hdev);
 	}
 
+	skb_queue_purge(&data->readq);
 	file->private_data = NULL;
 	kfree(data);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/bluetooth-vhci-purge-unhandled-skbs.patch queue-4.4/bluetooth-vhci-fix-open_timeout-vs.-hdev-race.patch