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

KASAN: slab-out-of-bounds Read in rtl_fw_do_work
Status: upstream: reported on 2020/12/11 20:11
Reported-by: syzbot+7b774a105bad5f282322@syzkaller.appspotmail.com
First crash: 44d, last: 44d

Sample crash report:

usb 1-1: Direct firmware load for rtlwifi/rtl8192cufw.bin failed with error -2
==================================================================
BUG: KASAN: slab-out-of-bounds in rtl_fw_do_work+0x407/0x430 drivers/net/wireless/realtek/rtlwifi/core.c:87
Read of size 8 at addr ffff888142b2ff58 by task kworker/0:6/7385

CPU: 0 PID: 7385 Comm: kworker/0:6 Not tainted 5.10.0-rc7-syzkaller #0
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+0x107/0x163 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 rtl_fw_do_work+0x407/0x430 drivers/net/wireless/realtek/rtlwifi/core.c:87
 request_firmware_work_func+0x12c/0x230 drivers/base/firmware_loader/main.c:1079
 process_one_work+0x933/0x1520 kernel/workqueue.c:2272
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418
 kthread+0x38c/0x460 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Allocated by task 16159:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461
 kmalloc include/linux/slab.h:557 [inline]
 tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_number_perm+0x1d5/0x590 security/tomoyo/file.c:723
 security_file_ioctl+0x50/0xb0 security/security.c:1481
 __do_sys_ioctl fs/ioctl.c:747 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0xb3/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 16159:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0x102/0x140 mm/kasan/common.c:422
 slab_free_hook mm/slub.c:1544 [inline]
 slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577
 slab_free mm/slub.c:3142 [inline]
 kfree+0xe5/0x5e0 mm/slub.c:4124
 tomoyo_realpath_from_path+0x191/0x620 security/tomoyo/realpath.c:291
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_number_perm+0x1d5/0x590 security/tomoyo/file.c:723
 security_file_ioctl+0x50/0xb0 security/security.c:1481
 __do_sys_ioctl fs/ioctl.c:747 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0xb3/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888142b2e000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 3928 bytes to the right of
 4096-byte region [ffff888142b2e000, ffff888142b2f000)
The buggy address belongs to the page:
page:00000000104f6cd2 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x142b28
head:00000000104f6cd2 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 dead000000000100 dead000000000122 ffff888100042140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888142b2fe00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888142b2fe80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888142b2ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                    ^
 ffff888142b2ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888142b30000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci2-upstream-usb	2020/12/11 18:22	https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing	3db4c21c	ba24ffcd	.config	log	report			info	davem@davemloft.net, kuba@kernel.org, kvalo@codeaurora.org, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, pkshih@realtek.com