Hello,
syzbot has tested the proposed patch but the reproducer still triggered
crash:
KASAN: slab-out-of-bounds Read in usb_reset_and_verify_device
usb 6-1: Using ep0 maxpacket: 16
usb 6-1: BOS total length 54, descriptor 168
usb 6-1: Old BOS ffff8881cd814f60 Len 0xa8
usb 6-1: New BOS ffff8881cd257ae0 Len 0xa8
==================================================================
BUG: KASAN: slab-out-of-bounds in memcmp+0xa6/0xb0 lib/string.c:904
Read of size 1 at addr ffff8881cd257c36 by task kworker/1:0/17
CPU: 1 PID: 17 Comm: kworker/1:0 Not tainted 5.3.0-rc5+ #0
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+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
memcmp+0xa6/0xb0 lib/string.c:904
memcmp include/linux/string.h:400 [inline]
descriptors_changed drivers/usb/core/hub.c:5579 [inline]
usb_reset_and_verify_device+0x5a8/0x1350 drivers/usb/core/hub.c:5736
usb_reset_device+0x4c1/0x920 drivers/usb/core/hub.c:5905
rt2x00usb_probe+0x53/0x7af
drivers/net/wireless/ralink/rt2x00/rt2x00usb.c:806
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2165
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+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2165
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
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Allocated by task 17:
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:557 [inline]
kzalloc include/linux/slab.h:748 [inline]
usb_get_bos_descriptor+0x1e4/0x315 drivers/usb/core/config.c:955
hub_port_init+0x169a/0x2d30 drivers/usb/core/hub.c:4837
usb_reset_and_verify_device+0x3aa/0x1350 drivers/usb/core/hub.c:5720
usb_reset_device+0x4c1/0x920 drivers/usb/core/hub.c:5905
rt2x00usb_probe+0x53/0x7af
drivers/net/wireless/ralink/rt2x00/rt2x00usb.c:806
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2165
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+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2165
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
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Freed by task 2190:
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:1474 [inline]
slab_free mm/slub.c:3016 [inline]
kfree+0xe4/0x2f0 mm/slub.c:3957
free_rb_tree_fname+0x7f/0xe0 fs/ext4/dir.c:404
ext4_htree_free_dir_info fs/ext4/dir.c:426 [inline]
ext4_release_dir+0x41/0x60 fs/ext4/dir.c:624
__fput+0x2d7/0x840 fs/file_table.c:280
task_work_run+0x13f/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x45f/0x580 arch/x86/entry/common.c:299
entry_SYSCALL_64_after_hwframe+0x49/0xbe
The buggy address belongs to the object at ffff8881cd257c00
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 54 bytes inside of
64-byte region [ffff8881cd257c00, ffff8881cd257c40)
The buggy address belongs to the page:
page:ffffea00073495c0 refcount:1 mapcount:0 mapping:ffff8881da003180
index:0xffff8881cd257f00
flags: 0x200000000000200(slab)
raw: 0200000000000200 ffffea00073442c0 0000001d0000001d ffff8881da003180
raw: ffff8881cd257f00 00000000802a0028 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8881cd257b00: 00 00 fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff8881cd257b80: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
ffff8881cd257c00: 00 00 00 00 00 00 06 fc fc fc fc fc fb fb fb fb
^
ffff8881cd257c80: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
ffff8881cd257d00: fc fc fc fc 00 00 00 00 00 00 00 00 fc fc fc fc
==================================================================
Tested on:
commit: eea39f24 usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=17cc619e600000
kernel config: https://syzkaller.appspot.com/x/.config?x=d0c62209eedfd54e
dashboard link: https://syzkaller.appspot.com/bug?extid=35f4d916c623118d576e
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
patch: https://syzkaller.appspot.com/x/patch.diff?x=10b73476600000
