KASAN: use-after-free Read in wdm_int_callback

From: syzbot
Date: Wed Aug 07 2019 - 10:28:09 EST

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Hello,

syzbot found the following crash on:

HEAD commit: e96407b4 usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=162e6352600000
kernel config: https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
dashboard link: https://syzkaller.appspot.com/bug?extid=1a3765ef3c0d49d36a75
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1a3765ef3c0d49d36a75@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in wdm_int_callback+0x459/0x4c0 drivers/usb/class/cdc-wdm.c:239
Read of size 8 at addr ffff8881cf42e410 by task udevd/6344

CPU: 0 PID: 6344 Comm: udevd Not tainted 5.3.0-rc2+ #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
print_address_description+0x6a/0x32c mm/kasan/report.c:351
__kasan_report.cold+0x1a/0x33 mm/kasan/report.c:482
kasan_report+0xe/0x12 mm/kasan/common.c:612
wdm_int_callback+0x459/0x4c0 drivers/usb/class/cdc-wdm.c:239
__usb_hcd_giveback_urb+0x1f2/0x470 drivers/usb/core/hcd.c:1757
usb_hcd_giveback_urb+0x368/0x420 drivers/usb/core/hcd.c:1822
dummy_timer+0x120f/0x2fa2 drivers/usb/gadget/udc/dummy_hcd.c:1965
call_timer_fn+0x179/0x650 kernel/time/timer.c:1322
expire_timers kernel/time/timer.c:1366 [inline]
__run_timers kernel/time/timer.c:1685 [inline]
__run_timers kernel/time/timer.c:1653 [inline]
run_timer_softirq+0x5cc/0x14b0 kernel/time/timer.c:1698
__do_softirq+0x221/0x912 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x178/0x1a0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:537 [inline]
smp_apic_timer_interrupt+0x12f/0x500 arch/x86/kernel/apic/apic.c:1095
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:828
</IRQ>
RIP: 0010:rb_prev+0xbd/0x130 lib/rbtree.c:550
Code: 75 20 48 89 d8 48 c1 e8 03 42 80 3c 28 00 75 67 4c 8b 23 48 89 dd 4c 89 e3 48 83 e3 fc 48 89 d8 75 c8 48 83 c4 08 5b 5d 41 5c <41> 5d c3 48 89 d0 48 8d 78 08 48 89 fa 48 c1 ea 03 80 3c 1a 00 75
RSP: 0018:ffff8881a447fba0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: ffff8881d6651920 RBX: 0000000000000004 RCX: ffffffff812666d0
RDX: 1ffff1103acca326 RSI: ffffffff815ab46e RDI: ffff8881d6651930
RBP: ffff8881d6651a20 R08: ffff8881cfdce000 R09: ffffed103a910587
R10: ffffed103a910586 R11: ffff8881d4882c33 R12: 0000000000000005
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
browse_rb mm/mmap.c:365 [inline]
validate_mm+0x3dd/0x610 mm/mmap.c:418
mmap_region+0xfbc/0x13c0 mm/mmap.c:1811
do_mmap+0x831/0x1070 mm/mmap.c:1561
do_mmap_pgoff include/linux/mm.h:2374 [inline]
vm_mmap_pgoff+0x195/0x1f0 mm/util.c:391
ksys_mmap_pgoff+0xd8/0x5b0 mm/mmap.c:1611
do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f2c0f046d0a
Code: b8 ff ff ff ff e9 fa fe ff ff 48 63 fb b8 03 00 00 00 0f 05 b8 ff ff ff ff e9 e6 fe ff ff 90 90 49 89 ca b8 09 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d fe c0 2a 00 31 d2 48 29 c2 64
RSP: 002b:00007ffe7106e018 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 000000000137e6b0 RCX: 00007f2c0f046d0a
RDX: 0000000000000003 RSI: 0000000000001000 RDI: 0000000000000000
RBP: 0000000000001000 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000420724
R13: 0000000000000002 R14: 0000000000420724 R15: 0000000000420724

Allocated by task 21732:
save_stack+0x1b/0x80 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_kmalloc mm/kasan/common.c:487 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:460
kmalloc include/linux/slab.h:552 [inline]
kzalloc include/linux/slab.h:748 [inline]
wdm_create+0x56/0x1720 drivers/usb/class/cdc-wdm.c:786
wdm_probe+0x220/0x2d0 drivers/usb/class/cdc-wdm.c:922
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x650 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:882
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2114
usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
really_probe+0x281/0x650 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:882
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2114
usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536
hub_port_connect drivers/usb/core/hub.c:5098 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 21732:
save_stack+0x1b/0x80 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_slab_free+0x130/0x180 mm/kasan/common.c:449
slab_free_hook mm/slub.c:1423 [inline]
slab_free_freelist_hook mm/slub.c:1470 [inline]
slab_free mm/slub.c:3012 [inline]
kfree+0xe4/0x2f0 mm/slub.c:3953
wdm_create+0x542/0x1720 drivers/usb/class/cdc-wdm.c:884
wdm_probe+0x220/0x2d0 drivers/usb/class/cdc-wdm.c:922
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x650 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:882
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2114
usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
really_probe+0x281/0x650 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:882
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2114
usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536
hub_port_connect drivers/usb/core/hub.c:5098 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8881cf42e400
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 16 bytes inside of
1024-byte region [ffff8881cf42e400, ffff8881cf42e800)
The buggy address belongs to the page:
page:ffffea00073d0b00 refcount:1 mapcount:0 mapping:ffff8881da002280 index:0x0 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 0000000000000000 0000000600000001 ffff8881da002280
raw: 0000000000000000 00000000000e000e 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881cf42e300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881cf42e380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff8881cf42e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff8881cf42e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881cf42e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Previous message: Mathieu Desnoyers: "[PATCH glibc 2.31 1/5] glibc: Perform rseq(2) registration at C startup and thread creation (v12)"
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