[ Upstream commit d4d8257754c3300ea2a465dadf8d2b02c713c920 ]

iso_buffer should be set to NULL after use and free in the while loop.
In the case of isochronous URB in the while loop, iso_buffer is
allocated and after sending it to server, buffer is deallocated. And
then, if the next URB in the while loop is not a isochronous pipe,
iso_buffer still holds the previously deallocated buffer address and
kfree tries to free wrong buffer address.

Fixes: ea44d190764b ("usbip: Implement SG support to vhci-hcd and stub driver")
Reported-by: Nkbuild test robot <lkp@intel.com>
Reported-by: NJulia Lawall <julia.lawall@lip6.fr>
Signed-off-by: NSuwan Kim <suwan.kim027@gmail.com>
Reviewed-by: NJulia Lawall <julia.lawall@lip6.fr>
Acked-by: NShuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20191022093017.8027-1-suwan.kim027@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>