[PATCH] media: ttusb-dec: Fix info-leak in ttusb_dec_send_command()

[PATCH] media: ttusb-dec: Fix info-leak in ttusb_dec_send_command()

[Tomas Bortoli]

The function at issue does not always initialize each byte allocated for 'b'
and can therefore leak uninitialized memory to a USB device in the call to usb_bulk_msg()

Use kzalloc() instead of kmalloc()


Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+0522702e9d67142379f1@syzkaller.appspotmail.com
---
Crash log:
==================================================================
BUG: KMSAN: kernel-usb-infoleak in usb_submit_urb+0x7ef/0x1f50 drivers/usb/core/urb.c:405
CPU: 1 PID: 3095 Comm: kworker/1:2 Not tainted 5.2.0-rc4+ #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x191/0x1f0 lib/dump_stack.c:113
 kmsan_report+0x162/0x2d0 mm/kmsan/kmsan_report.c:109
 kmsan_internal_check_memory+0x974/0xa80 mm/kmsan/kmsan.c:573
 kmsan_handle_urb+0x28/0x40 mm/kmsan/kmsan_hooks.c:617
 usb_submit_urb+0x7ef/0x1f50 drivers/usb/core/urb.c:405
 usb_start_wait_urb+0x143/0x410 drivers/usb/core/message.c:58
 usb_bulk_msg+0x811/0x920 drivers/usb/core/message.c:257
 ttusb_dec_send_command+0x47d/0xd50 drivers/media/usb/ttusb-dec/ttusb_dec.c:345
 ttusb_dec_get_stb_state drivers/media/usb/ttusb-dec/ttusb_dec.c:393 [inline]
 ttusb_dec_init_stb drivers/media/usb/ttusb-dec/ttusb_dec.c:1421 [inline]
 ttusb_dec_probe+0xe31/0x4df0 drivers/media/usb/ttusb-dec/ttusb_dec.c:1680
 usb_probe_interface+0xd19/0x1310 drivers/usb/core/driver.c:361
 really_probe+0x1344/0x1d90 drivers/base/dd.c:513
 driver_probe_device+0x1ba/0x510 drivers/base/dd.c:670
 __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:777
 bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
 __device_attach+0x489/0x750 drivers/base/dd.c:843
 device_initial_probe+0x4a/0x60 drivers/base/dd.c:890
 bus_probe_device+0x131/0x390 drivers/base/bus.c:514
 device_add+0x25b5/0x2df0 drivers/base/core.c:2111
 usb_set_configuration+0x309f/0x3710 drivers/usb/core/message.c:2027
 generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210
 usb_probe_device+0x146/0x200 drivers/usb/core/driver.c:266
 really_probe+0x1344/0x1d90 drivers/base/dd.c:513
 driver_probe_device+0x1ba/0x510 drivers/base/dd.c:670
 __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:777
 bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
 __device_attach+0x489/0x750 drivers/base/dd.c:843
 device_initial_probe+0x4a/0x60 drivers/base/dd.c:890
 bus_probe_device+0x131/0x390 drivers/base/bus.c:514
 device_add+0x25b5/0x2df0 drivers/base/core.c:2111
 usb_new_device+0x23e5/0x2fb0 drivers/usb/core/hub.c:2534
 hub_port_connect drivers/usb/core/hub.c:5089 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
 port_event drivers/usb/core/hub.c:5350 [inline]
 hub_event+0x5853/0x7320 drivers/usb/core/hub.c:5432
 process_one_work+0x1572/0x1f00 kernel/workqueue.c:2269
 worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355
Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:200 [inline]
 kmsan_internal_poison_shadow+0x53/0xa0 mm/kmsan/kmsan.c:159
 kmsan_kmalloc+0xa4/0x130 mm/kmsan/kmsan_hooks.c:178
 kmem_cache_alloc_trace+0x503/0xae0 mm/slub.c:2793
 kmalloc include/linux/slab.h:547 [inline]
 ttusb_dec_send_command+0x155/0xd50 drivers/media/usb/ttusb-dec/ttusb_dec.c:322
 ttusb_dec_get_stb_state drivers/media/usb/ttusb-dec/ttusb_dec.c:393 [inline]
 ttusb_dec_init_stb drivers/media/usb/ttusb-dec/ttusb_dec.c:1421 [inline]
 ttusb_dec_probe+0xe31/0x4df0 drivers/media/usb/ttusb-dec/ttusb_dec.c:1680
 usb_probe_interface+0xd19/0x1310 drivers/usb/core/driver.c:361
 really_probe+0x1344/0x1d90 drivers/base/dd.c:513
 driver_probe_device+0x1ba/0x510 drivers/base/dd.c:670
 __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:777
 bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
 __device_attach+0x489/0x750 drivers/base/dd.c:843
 device_initial_probe+0x4a/0x60 drivers/base/dd.c:890
 bus_probe_device+0x131/0x390 drivers/base/bus.c:514
 device_add+0x25b5/0x2df0 drivers/base/core.c:2111
 usb_set_configuration+0x309f/0x3710 drivers/usb/core/message.c:2027
 generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210
 usb_probe_device+0x146/0x200 drivers/usb/core/driver.c:266
 really_probe+0x1344/0x1d90 drivers/base/dd.c:513
 driver_probe_device+0x1ba/0x510 drivers/base/dd.c:670
 __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:777
 bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454
 __device_attach+0x489/0x750 drivers/base/dd.c:843
 device_initial_probe+0x4a/0x60 drivers/base/dd.c:890
 bus_probe_device+0x131/0x390 drivers/base/bus.c:514
 device_add+0x25b5/0x2df0 drivers/base/core.c:2111
 usb_new_device+0x23e5/0x2fb0 drivers/usb/core/hub.c:2534
 hub_port_connect drivers/usb/core/hub.c:5089 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
 port_event drivers/usb/core/hub.c:5350 [inline]
 hub_event+0x5853/0x7320 drivers/usb/core/hub.c:5432
 process_one_work+0x1572/0x1f00 kernel/workqueue.c:2269
 worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355
Bytes 4-63 of 64 are uninitialized
Memory access of size 64 starts at ffff8880ba4efac0
==================================================================

 drivers/media/usb/ttusb-dec/ttusb_dec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/ttusb-dec/ttusb_dec.c b/drivers/media/usb/ttusb-dec/ttusb_dec.c
index 1d0afa340f47..3198f9624b7c 100644
--- a/drivers/media/usb/ttusb-dec/ttusb_dec.c
+++ b/drivers/media/usb/ttusb-dec/ttusb_dec.c
@@ -319,7 +319,7 @@ static int ttusb_dec_send_command(struct ttusb_dec *dec, const u8 command,
 
 	dprintk("%s\n", __func__);
 
-	b = kmalloc(COMMAND_PACKET_SIZE + 4, GFP_KERNEL);
+	b = kzalloc(COMMAND_PACKET_SIZE + 4, GFP_KERNEL);
 	if (!b)
 		return -ENOMEM;
 
-- 
2.11.0