From c171654caa875919be3c533d3518da8be5be966e Mon Sep 17 00:00:00 2001 From: "Shuah Khan (Samsung OSG)" Date: Tue, 15 May 2018 17:57:23 -0600 Subject: [PATCH] usbip: usbip_host: fix bad unlock balance during stub_probe() 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) Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/usbip/stub_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c index 41c7b9d..bf8a5fe 100644 --- a/drivers/usb/usbip/stub_main.c +++ b/drivers/usb/usbip/stub_main.c @@ -82,7 +82,8 @@ struct bus_id_priv *get_busid_priv(const char *busid) 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) -- 2.7.4