KASAN: slab-out-of-bounds Read in ds_probe

KASAN: slab-out-of-bounds Read in ds_probe

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    9a33b369 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan/tree/usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=13eb726b200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=23e37f59d94ddd15
dashboard link: https://syzkaller.appspot.com/bug?extid=d65f673b847a1a96cdba
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1340b55b200000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12e436f3200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d65f673b847a1a96cdba@syzkaller.appspotmail.com

usb 1-1: config 0 has no interface number 0
usb 1-1: New USB device found, idVendor=04fa, idProduct=2490,  
bcdDevice=74.f9
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
==================================================================
BUG: KASAN: slab-out-of-bounds in ds_probe+0x604/0x760  
drivers/w1/masters/ds2490.c:1019
Read of size 1 at addr ffff8880a7c45fe2 by task kworker/0:1/12

CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.1.0-rc4-319354-g9a33b36 #3
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+0xe8/0x16e lib/dump_stack.c:113
  print_address_description+0x6c/0x236 mm/kasan/report.c:187
  kasan_report.cold+0x1a/0x3c mm/kasan/report.c:317
  ds_probe+0x604/0x760 drivers/w1/masters/ds2490.c:1019
  usb_probe_interface+0x31d/0x820 drivers/usb/core/driver.c:361
  really_probe+0x2da/0xb10 drivers/base/dd.c:509
  driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
  __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
  bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
  __device_attach+0x223/0x3a0 drivers/base/dd.c:844
  bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
  device_add+0xad2/0x16e0 drivers/base/core.c:2106
  usb_set_configuration+0xdf7/0x1740 drivers/usb/core/message.c:2021
  generic_probe+0xa2/0xda drivers/usb/core/generic.c:210
  usb_probe_device+0xc0/0x150 drivers/usb/core/driver.c:266
  really_probe+0x2da/0xb10 drivers/base/dd.c:509
  driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
  __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
  bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
  __device_attach+0x223/0x3a0 drivers/base/dd.c:844
  bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
  device_add+0xad2/0x16e0 drivers/base/core.c:2106
  usb_new_device.cold+0x537/0xccf 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+0x138e/0x3b00 drivers/usb/core/hub.c:5432
  process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
  worker_thread+0x9b/0xe20 kernel/workqueue.c:2415
  kthread+0x313/0x420 kernel/kthread.c:253
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 12:
  set_track mm/kasan/common.c:87 [inline]
  __kasan_kmalloc mm/kasan/common.c:497 [inline]
  __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:470
  kmalloc include/linux/slab.h:552 [inline]
  kzalloc include/linux/slab.h:742 [inline]
  usb_parse_configuration drivers/usb/core/config.c:710 [inline]
  usb_get_configuration+0xc4c/0x32b0 drivers/usb/core/config.c:882
  usb_enumerate_device drivers/usb/core/hub.c:2367 [inline]
  usb_new_device+0x2fe/0x450 drivers/usb/core/hub.c:2503
  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+0x138e/0x3b00 drivers/usb/core/hub.c:5432
  process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
  worker_thread+0x9b/0xe20 kernel/workqueue.c:2415
  kthread+0x313/0x420 kernel/kthread.c:253
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Freed by task 1258:
  set_track mm/kasan/common.c:87 [inline]
  __kasan_slab_free+0x130/0x180 mm/kasan/common.c:459
  slab_free_hook mm/slub.c:1429 [inline]
  slab_free_freelist_hook+0x5e/0x140 mm/slub.c:1456
  slab_free mm/slub.c:3003 [inline]
  kfree+0xce/0x290 mm/slub.c:3958
  security_task_free+0x9a/0xf0 security/security.c:1470
  __put_task_struct+0xec/0x4d0 kernel/fork.c:724
  put_task_struct include/linux/sched/task.h:98 [inline]
  delayed_put_task_struct+0x189/0x290 kernel/exit.c:181
  __rcu_reclaim kernel/rcu/rcu.h:227 [inline]
  rcu_do_batch kernel/rcu/tree.c:2475 [inline]
  invoke_rcu_callbacks kernel/rcu/tree.c:2788 [inline]
  rcu_core+0x83b/0x1a80 kernel/rcu/tree.c:2769
  __do_softirq+0x22a/0x8cd kernel/softirq.c:293

The buggy address belongs to the object at ffff8880a7c45f60
  which belongs to the cache kmalloc-64 of size 64
The buggy address is located 66 bytes to the right of
  64-byte region [ffff8880a7c45f60, ffff8880a7c45fa0)
The buggy address belongs to the page:
page:ffffea00029f1140 count:1 mapcount:0 mapping:ffff88812c3f5600 index:0x0
flags: 0xfff00000000200(slab)
raw: 00fff00000000200 ffffea00025f69c0 0000000500000005 ffff88812c3f5600
raw: 0000000000000000 00000000802a002a 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8880a7c45e80: fc fc fc fc 00 00 00 00 00 00 00 fc fc fc fc fc
  ffff8880a7c45f00: fb fb fb fb fb fb fb fb fc fc fc fc 00 00 00 00
> ffff8880a7c45f80: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                        ^
  ffff8880a7c46000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff8880a7c46080: 00 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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Re: KASAN: slab-out-of-bounds Read in ds_probe

[Alan Stern]

On Wed, 17 Apr 2019, syzbot wrote:

> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    9a33b369 usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan/tree/usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=13eb726b200000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=23e37f59d94ddd15
> dashboard link: https://syzkaller.appspot.com/bug?extid=d65f673b847a1a96cdba
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1340b55b200000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12e436f3200000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+d65f673b847a1a96cdba@syzkaller.appspotmail.com
> 
> usb 1-1: config 0 has no interface number 0
> usb 1-1: New USB device found, idVendor=04fa, idProduct=2490,  
> bcdDevice=74.f9
> usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> usb 1-1: config 0 descriptor??
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in ds_probe+0x604/0x760  
> drivers/w1/masters/ds2490.c:1019
> Read of size 1 at addr ffff8880a7c45fe2 by task kworker/0:1/12
> 
> CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.1.0-rc4-319354-g9a33b36 #3
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
> Google 01/01/2011
> Workqueue: usb_hub_wq hub_event

Looks like a typical misunderstanding of how the interface altsettings 
array works.

Alan Stern


#syz test: https://github.com/google/kasan.git usb-fuzzer

--- a/drivers/w1/masters/ds2490.c
+++ b/drivers/w1/masters/ds2490.c
@@ -1016,15 +1016,15 @@ static int ds_probe(struct usb_interface
 	/* alternative 3, 1ms interrupt (greatly speeds search), 64 byte bulk */
 	alt = 3;
 	err = usb_set_interface(dev->udev,
-		intf->altsetting[alt].desc.bInterfaceNumber, alt);
+		intf->cur_altsetting->desc.bInterfaceNumber, alt);
 	if (err) {
 		dev_err(&dev->udev->dev, "Failed to set alternative setting %d "
 			"for %d interface: err=%d.\n", alt,
-			intf->altsetting[alt].desc.bInterfaceNumber, err);
+			intf->cur_altsetting->desc.bInterfaceNumber, err);
 		goto err_out_clear;
 	}
 
-	iface_desc = &intf->altsetting[alt];
+	iface_desc = intf->cur_altsetting;
 	if (iface_desc->desc.bNumEndpoints != NUM_EP-1) {
 		pr_info("Num endpoints=%d. It is not DS9490R.\n",
 			iface_desc->desc.bNumEndpoints);

Re: KASAN: slab-out-of-bounds Read in ds_probe

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger  
crash:

Reported-and-tested-by:  
syzbot+d65f673b847a1a96cdba@syzkaller.appspotmail.com

Tested on:

commit:         d34f9519 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan/tree/usb-fuzzer
kernel config:  https://syzkaller.appspot.com/x/.config?x=c73d1bb5aeaeae20
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1588b96b200000

Note: testing is done by a robot and is best-effort only.