[PATCH 4.14 14/43] qmi_wwan: Fix out-of-bounds read

Greg Kroah-Hartman
2019-07-02T08:12:19Z

commit 904d88d743b0c94092c5117955eab695df8109e8 upstream.

The syzbot reported

Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
print_address_description+0x67/0x231 mm/kasan/report.c:188
__kasan_report.cold+0x1a/0x32 mm/kasan/report.c:317
kasan_report+0xe/0x20 mm/kasan/common.c:614
qmi_wwan_probe+0x342/0x360 drivers/net/usb/qmi_wwan.c:1417
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x660 drivers/base/dd.c:509
driver_probe_device+0x104/0x210 drivers/base/dd.c:670
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454

Caused by too many confusing indirections and casts.
id->driver_info is a pointer stored in a long. We want the
pointer here, not the address of it.

Thanks-to: Hillf Danton <hdanton@sina.com>
Reported-by: syzbot+b68605d7fadd21510de1@syzkaller.appspotmail.com
Cc: Kristian Evensen <kristian.evensen@gmail.com>
Fixes: e4bf63482c30 ("qmi_wwan: Add quirk for Quectel dynamic config")
Signed-off-by: Bjørn Mork <bjorn@mork.no>

[Upstream commit did not apply because I shuffled two lines in the
backport. The fixes tag for 4.14 is 3a6a5107ceb3.]

Signed-off-by: Kristian Evensen <kristian.evensen@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/usb/qmi_wwan.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
index c2d6c501dd85..063daa3435e4 100644
--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c
@@ -1395,14 +1395,14 @@ static int qmi_wwan_probe(struct usb_interface *intf,
return -ENODEV;
}

- info = (void *)&id->driver_info;
-
/* Several Quectel modems supports dynamic interface configuration, so
* we need to match on class/subclass/protocol. These values are
* identical for the diagnostic- and QMI-interface, but bNumEndpoints is
* different. Ignore the current interface if the number of endpoints
* equals the number for the diag interface (two).
*/
+ info = (void *)id->driver_info;
+
if (info->data & QMI_WWAN_QUIRK_QUECTEL_DYNCFG) {
if (desc->bNumEndpoints == 2)
return -ENODEV;
--
2.20.1