[PATCH 4.4 38/86] Bluetooth: vhci: purge unhandled skbs

Greg Kroah-Hartman
2016-05-30T22:01:42Z

From: Jiri Slaby <jslaby@suse.cz>

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]

Fixes: 23424c0d31 (Bluetooth: Add support creating virtual AMP controllers)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -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);