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SubjectRe: [RFT] lan78xx: FIX use-after-free in lan78xx_write_reg
On Wed, Sep 27, 2017 at 2:06 PM, Andrey Konovalov <andreyknvl@google.com> wrote:
> On Wed, Sep 27, 2017 at 1:18 PM, Arvind Yadav <arvind.yadav.cs@gmail.com> wrote:
>> We are not releasing 'buf' memory on failure or disconnect a device.
>>
>> Adding 'u8 *buf' as part of 'lan78xx_net' structure to make proper
>> handle for 'buf'.
>> Now releasing 'buf' memory on failure. It's allocate first in
>> lan78xx_probe() and it should be freed last in lan78xx_disconnect().
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
>
> Hi Arvind,
>
> I've tried your patch and still see a crash.
>
> Thanks!
>
> lan78xx 1-1:90.0 (unnamed net_device) (uninitialized): can't register MDIO bus
> lan78xx: probe of 1-1:90.0 failed with error -5
> usb 1-1: USB disconnect, device number 2
> ==================================================================
> BUG: KASAN: use-after-free in lan78xx_write_reg.isra.21+0x1a8/0x1b0
> Read of size 8 at addr ffff880063dfac40 by task kworker/1:1/1152

It seems that the bug is caused by the fact that the
lan78xx_deferred_multicast_write() work is not shut down on
lan78xx_probe() failure.

>
> CPU: 1 PID: 1152 Comm: kworker/1:1 Not tainted
> 4.14.0-rc2-42660-g24b7bd59eec0-dirty #274
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Workqueue: events lan78xx_deferred_multicast_write
> Call Trace:
> __dump_stack lib/dump_stack.c:16
> dump_stack+0x292/0x395 lib/dump_stack.c:52
> print_address_description+0x78/0x280 mm/kasan/report.c:252
> kasan_report_error mm/kasan/report.c:351
> kasan_report+0x23d/0x350 mm/kasan/report.c:409
> __asan_report_load8_noabort+0x19/0x20 mm/kasan/report.c:430
> lan78xx_write_reg.isra.21+0x1a8/0x1b0 drivers/net/usb/lan78xx.c:459
> lan78xx_deferred_multicast_write+0x10d/0x1a0 drivers/net/usb/lan78xx.c:1043
> process_one_work+0xc7f/0x1db0 kernel/workqueue.c:2119
> worker_thread+0x221/0x1850 kernel/workqueue.c:2253
> kthread+0x3a1/0x470 kernel/kthread.c:231
> ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
>
> Allocated by task 1848:
> save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
> save_stack+0x43/0xd0 mm/kasan/kasan.c:447
> set_track mm/kasan/kasan.c:459
> kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
> __kmalloc_node+0x192/0x480 mm/slub.c:3827
> kmalloc_node ./include/linux/slab.h:535
> kvmalloc_node+0x69/0xd0 mm/util.c:397
> kvmalloc ./include/linux/mm.h:529
> kvzalloc ./include/linux/mm.h:537
> alloc_netdev_mqs+0x173/0xea0 net/core/dev.c:8023
> alloc_etherdev_mqs+0x38/0x40 net/ethernet/eth.c:391
> lan78xx_probe+0x13a/0x3020 drivers/net/usb/lan78xx.c:3545
> usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361
> really_probe drivers/base/dd.c:413
> driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
> __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
> bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
> __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
> device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
> bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
> device_add+0xd0b/0x1660 drivers/base/core.c:1835
> usb_set_configuration+0x104e/0x1870 drivers/usb/core/message.c:1932
> generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174
> usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266
> really_probe drivers/base/dd.c:413
> driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
> __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
> bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
> __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
> device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
> bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
> device_add+0xd0b/0x1660 drivers/base/core.c:1835
> usb_new_device+0x7b8/0x1020 drivers/usb/core/hub.c:2457
> hub_port_connect drivers/usb/core/hub.c:4903
> hub_port_connect_change drivers/usb/core/hub.c:5009
> port_event drivers/usb/core/hub.c:5115
> hub_event+0x194d/0x3740 drivers/usb/core/hub.c:5195
> process_one_work+0xc7f/0x1db0 kernel/workqueue.c:2119
> worker_thread+0x221/0x1850 kernel/workqueue.c:2253
> kthread+0x3a1/0x470 kernel/kthread.c:231
> ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
>
> Freed by task 1848:
> save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
> save_stack+0x43/0xd0 mm/kasan/kasan.c:447
> set_track mm/kasan/kasan.c:459
> kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:524
> slab_free_hook mm/slub.c:1390
> slab_free_freelist_hook mm/slub.c:1412
> slab_free mm/slub.c:2988
> kfree+0xf6/0x2f0 mm/slub.c:3919
> kvfree+0x3b/0x60 mm/util.c:416
> netdev_freemem net/core/dev.c:7975
> free_netdev+0x304/0x3c0 net/core/dev.c:8137
> lan78xx_probe+0x21a4/0x3020 drivers/net/usb/lan78xx.c:3649
> usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361
> really_probe drivers/base/dd.c:413
> driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
> __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
> bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
> __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
> device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
> bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
> device_add+0xd0b/0x1660 drivers/base/core.c:1835
> usb_set_configuration+0x104e/0x1870 drivers/usb/core/message.c:1932
> generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174
> usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266
> really_probe drivers/base/dd.c:413
> driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
> __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
> bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
> __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
> device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
> bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
> device_add+0xd0b/0x1660 drivers/base/core.c:1835
> usb_new_device+0x7b8/0x1020 drivers/usb/core/hub.c:2457
> hub_port_connect drivers/usb/core/hub.c:4903
> hub_port_connect_change drivers/usb/core/hub.c:5009
> port_event drivers/usb/core/hub.c:5115
> hub_event+0x194d/0x3740 drivers/usb/core/hub.c:5195
> process_one_work+0xc7f/0x1db0 kernel/workqueue.c:2119
> worker_thread+0x221/0x1850 kernel/workqueue.c:2253
> kthread+0x3a1/0x470 kernel/kthread.c:231
> ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
>
> The buggy address belongs to the object at ffff880063dfa100
> which belongs to the cache kmalloc-8192 of size 8192
> The buggy address is located 2880 bytes inside of
> 8192-byte region [ffff880063dfa100, ffff880063dfc100)
> The buggy address belongs to the page:
> page:ffffea00018f7e00 count:1 mapcount:0 mapping: (null)
> index:0x0 compound_mapcount: 0
> flags: 0x100000000008100(slab|head)
> raw: 0100000000008100 0000000000000000 0000000000000000 0000000100030003
> raw: ffffea0001afd800 0000000300000003 ffff88006c402a80 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffff880063dfab00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff880063dfab80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>ffff880063dfac00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff880063dfac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff880063dfad00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>> ---
>> drivers/net/usb/lan78xx.c | 14 +++++++++-----
>> 1 file changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
>> index b99a7fb..e653982 100644
>> --- a/drivers/net/usb/lan78xx.c
>> +++ b/drivers/net/usb/lan78xx.c
>> @@ -402,6 +402,7 @@ struct lan78xx_net {
>> struct statstage stats;
>>
>> struct irq_domain_data domain_data;
>> + u8 *buf;
>> };
>>
>> /* define external phy id */
>> @@ -3470,6 +3471,9 @@ static void lan78xx_disconnect(struct usb_interface *intf)
>>
>> usb_scuttle_anchored_urbs(&dev->deferred);
>>
>> + kfree(dev->buf);
>> + dev->buf = NULL;
>> +
>> lan78xx_unbind(dev, intf);
>>
>> usb_kill_urb(dev->urb_intr);
>> @@ -3520,7 +3524,6 @@ static int lan78xx_probe(struct usb_interface *intf,
>> int ret;
>> unsigned maxp;
>> unsigned period;
>> - u8 *buf = NULL;
>>
>> udev = interface_to_usbdev(intf);
>> udev = usb_get_dev(udev);
>> @@ -3588,16 +3591,15 @@ static int lan78xx_probe(struct usb_interface *intf,
>> period = dev->ep_intr->desc.bInterval;
>>
>> maxp = usb_maxpacket(dev->udev, dev->pipe_intr, 0);
>> - buf = kmalloc(maxp, GFP_KERNEL);
>> - if (buf) {
>> + dev->buf = kmalloc(maxp, GFP_KERNEL);
>> + if (dev->buf) {
>> dev->urb_intr = usb_alloc_urb(0, GFP_KERNEL);
>> if (!dev->urb_intr) {
>> ret = -ENOMEM;
>> - kfree(buf);
>> goto out3;
>> } else {
>> usb_fill_int_urb(dev->urb_intr, dev->udev,
>> - dev->pipe_intr, buf, maxp,
>> + dev->pipe_intr, dev->buf, maxp,
>> intr_complete, dev, period);
>> }
>> }
>> @@ -3626,6 +3628,8 @@ static int lan78xx_probe(struct usb_interface *intf,
>> return 0;
>>
>> out3:
>> + kfree(dev->buf);
>> + dev->buf = NULL;
>> lan78xx_unbind(dev, intf);
>> out2:
>> free_netdev(netdev);
>> --
>> 1.9.1
>>

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