4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Shuah Khan (Samsung OSG) shuah@kernel.org
commit c171654caa875919be3c533d3518da8be5be966e upstream.
stub_probe() calls put_busid_priv() in an error path when device isn't found in the busid_table. Fix it by making put_busid_priv() safe to be called with null struct bus_id_priv pointer.
This problem happens when "usbip bind" is run without loading usbip_host driver and then running modprobe. The first failed bind attempt unbinds the device from the original driver and when usbip_host is modprobed, stub_probe() runs and doesn't find the device in its busid table and calls put_busid_priv(0 with null bus_id_priv pointer.
usbip-host 3-10.2: 3-10.2 is not in match_busid table... skip!
[ 367.359679] ===================================== [ 367.359681] WARNING: bad unlock balance detected! [ 367.359683] 4.17.0-rc4+ #5 Not tainted [ 367.359685] ------------------------------------- [ 367.359688] modprobe/2768 is trying to release lock ( [ 367.359689] ================================================================== [ 367.359696] BUG: KASAN: null-ptr-deref in print_unlock_imbalance_bug+0x99/0x110 [ 367.359699] Read of size 8 at addr 0000000000000058 by task modprobe/2768
[ 367.359705] CPU: 4 PID: 2768 Comm: modprobe Not tainted 4.17.0-rc4+ #5
Fixes: 22076557b07c ("usbip: usbip_host: fix NULL-ptr deref and use-after-free errors") in usb-linus Signed-off-by: Shuah Khan (Samsung OSG) shuah@kernel.org Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/usbip/stub_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/usb/usbip/stub_main.c +++ b/drivers/usb/usbip/stub_main.c @@ -96,7 +96,8 @@ struct bus_id_priv *get_busid_priv(const
void put_busid_priv(struct bus_id_priv *bid) { - spin_unlock(&bid->busid_lock); + if (bid) + spin_unlock(&bid->busid_lock); }
static int add_match_busid(char *busid)