On Thu, 14 Apr 2016 16:41:34 +0200,
Marcel Holtmann wrote:
>
> Hi Takashi,
>
> >>> 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@xxxxxxx>
> >>> Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
> >>> Cc: Gustavo Padovan <gustavo@xxxxxxxxxxx>
> >>> Cc: Johan Hedberg <johan.hedberg@xxxxxxxxx>
> >>> Cc: <linux-bluetooth@xxxxxxxxxxxxxxx>
> >>> Cc: stable 3.13+ <stable@xxxxxxxxxxxxxxx>
> >>> ---
> >>> drivers/bluetooth/hci_vhci.c | 1 +
> >>> 1 file changed, 1 insertion(+)
> >>
> >> patch has been applied to bluetooth-next tree.
> >
> > Could you check another race of vhci mentioned in the thread?
> > https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1106134.html
> >
> > If the suggested fix is OK, I'll submit a properly cooked patch.
>
> lets get the patch send to the mailing list and then I can have a look at it. I might need to test the final patch so that it works with legacy userspace.
Alright, will submit it soon later.
thanks,
Takashi
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