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SubjectKASAN: slab-out-of-bounds Read in p54u_load_firmware_cb

syzbot found the following crash on:

HEAD commit: 43151d6c usb-fuzzer: main usb gadget fuzzer driver
git tree: usb-fuzzer
console output:
kernel config:
dashboard link:
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:

cx231xx 2-1:0.1: New device @ 480 Mbps (2040:b111) with 1 interfaces
cx231xx 2-1:0.1: Not found matching IAD interface
usb 6-1: Direct firmware load for isl3887usb failed with error -2
usb 6-1: Firmware not found.
BUG: KASAN: slab-out-of-bounds in p54u_load_firmware_cb.cold+0x97/0x13a
Read of size 8 at addr ffff888099763588 by task kworker/0:1/12

CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.1.0-rc3-319004-g43151d6 #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: events request_firmware_work_func
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
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 7931:
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
slab_post_alloc_hook mm/slab.h:437 [inline]
slab_alloc_node mm/slub.c:2756 [inline]
__kmalloc_node_track_caller+0xf3/0x320 mm/slub.c:4372
__kmalloc_reserve.isra.0+0x3e/0xf0 net/core/skbuff.c:140
__alloc_skb+0xf4/0x5a0 net/core/skbuff.c:208
alloc_skb include/linux/skbuff.h:1058 [inline]
alloc_uevent_skb+0x7b/0x210 lib/kobject_uevent.c:289
uevent_net_broadcast_untagged lib/kobject_uevent.c:325 [inline]
kobject_uevent_net_broadcast lib/kobject_uevent.c:408 [inline]
kobject_uevent_env+0x865/0x13d0 lib/kobject_uevent.c:589
udc_bind_to_driver+0x33e/0x5e0 drivers/usb/gadget/udc/core.c:1357
usb_gadget_probe_driver+0x23f/0x380 drivers/usb/gadget/udc/core.c:1408
fuzzer_ioctl_run drivers/usb/gadget/fuzzer/fuzzer.c:718 [inline]
fuzzer_ioctl+0x15be/0x1d90 drivers/usb/gadget/fuzzer/fuzzer.c:1130
full_proxy_unlocked_ioctl+0x11b/0x180 fs/debugfs/file.c:205
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xced/0x12f0 fs/ioctl.c:696
ksys_ioctl+0xa0/0xc0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x74/0xb0 fs/ioctl.c:718
do_syscall_64+0xcf/0x4f0 arch/x86/entry/common.c:290

Freed by task 805:
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
skb_free_head+0x90/0xb0 net/core/skbuff.c:557
skb_release_data+0x543/0x8b0 net/core/skbuff.c:577
skb_release_all+0x4b/0x60 net/core/skbuff.c:631
__kfree_skb net/core/skbuff.c:645 [inline]
consume_skb net/core/skbuff.c:705 [inline]
consume_skb+0xc5/0x2f0 net/core/skbuff.c:699
skb_free_datagram+0x1b/0xf0 net/core/datagram.c:329
netlink_recvmsg+0x663/0xea0 net/netlink/af_netlink.c:2004
sock_recvmsg_nosec net/socket.c:881 [inline]
sock_recvmsg net/socket.c:888 [inline]
sock_recvmsg+0xd1/0x110 net/socket.c:884
___sys_recvmsg+0x278/0x5a0 net/socket.c:2422
__sys_recvmsg+0xee/0x1b0 net/socket.c:2471
do_syscall_64+0xcf/0x4f0 arch/x86/entry/common.c:290

The buggy address belongs to the object at ffff888099763180
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 8 bytes to the right of
1024-byte region [ffff888099763180, ffff888099763580)
The buggy address belongs to the page:
page:ffffea000265d800 count:1 mapcount:0 mapping:ffff88812c3f4a00 index:0x0
compound_mapcount: 0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000200 ffff88812c3f4a00
raw: 0000000000000000 00000000000e000e 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888099763480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888099763500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888099763580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888099763600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888099763680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

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