Re: KASAN: use-after-free Read in hfa384x_usbin_callback

[Qiujun Huang <anenbupt@gmail.com>]

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#syz test: https://github.com/google/kasan.git e17994d1

On Mon, Mar 23, 2020 at 8:39 PM syzbot
<syzbot+a57b24d359dc5577634a@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    e17994d1 usb: core: kcov: collect coverage from usb comple..
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=15217373e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5d64370c438bc60
> dashboard link: https://syzkaller.appspot.com/bug?extid=a57b24d359dc5577634a
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14a720ade00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1467b755e00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+a57b24d359dc5577634a@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KASAN: use-after-free in memcpy include/linux/string.h:381 [inline]
> BUG: KASAN: use-after-free in skb_put_data include/linux/skbuff.h:2284 [inline]
> BUG: KASAN: use-after-free in hfa384x_int_rxmonitor drivers/staging/wlan-ng/hfa384x_usb.c:3412 [inline]
> BUG: KASAN: use-after-free in hfa384x_usbin_rx drivers/staging/wlan-ng/hfa384x_usb.c:3312 [inline]
> BUG: KASAN: use-after-free in hfa384x_usbin_callback+0x1993/0x2360 drivers/staging/wlan-ng/hfa384x_usb.c:3026
> Read of size 34945 at addr ffff8881cda9f33c by task swapper/0/0
>
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc5-syzkaller #0
> 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+0xef/0x16e lib/dump_stack.c:118
>  print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374
>  __kasan_report.cold+0x37/0x77 mm/kasan/report.c:506
>  kasan_report+0xe/0x20 mm/kasan/common.c:641
>  check_memory_region_inline mm/kasan/generic.c:185 [inline]
>  check_memory_region+0x152/0x1c0 mm/kasan/generic.c:192
>  memcpy+0x20/0x50 mm/kasan/common.c:127
>  memcpy include/linux/string.h:381 [inline]
>  skb_put_data include/linux/skbuff.h:2284 [inline]
>  hfa384x_int_rxmonitor drivers/staging/wlan-ng/hfa384x_usb.c:3412 [inline]
>  hfa384x_usbin_rx drivers/staging/wlan-ng/hfa384x_usb.c:3312 [inline]
>  hfa384x_usbin_callback+0x1993/0x2360 drivers/staging/wlan-ng/hfa384x_usb.c:3026
>  __usb_hcd_giveback_urb+0x29a/0x550 drivers/usb/core/hcd.c:1650
>  usb_hcd_giveback_urb+0x368/0x420 drivers/usb/core/hcd.c:1716
>  dummy_timer+0x1258/0x32ae drivers/usb/gadget/udc/dummy_hcd.c:1966
>  call_timer_fn+0x195/0x6f0 kernel/time/timer.c:1404
>  expire_timers kernel/time/timer.c:1449 [inline]
>  __run_timers kernel/time/timer.c:1773 [inline]
>  __run_timers kernel/time/timer.c:1740 [inline]
>  run_timer_softirq+0x5f9/0x1500 kernel/time/timer.c:1786
>  __do_softirq+0x21e/0x950 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:546 [inline]
>  smp_apic_timer_interrupt+0x141/0x540 arch/x86/kernel/apic/apic.c:1146
>  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
>  </IRQ>
> RIP: 0010:default_idle+0x28/0x300 arch/x86/kernel/process.c:696
> Code: cc cc 41 56 41 55 65 44 8b 2d 44 77 72 7a 41 54 55 53 0f 1f 44 00 00 e8 b6 62 b5 fb e9 07 00 00 00 0f 00 2d ea 0c 53 00 fb f4 <65> 44 8b 2d 20 77 72 7a 0f 1f 44 00 00 5b 5d 41 5c 41 5d 41 5e c3
> RSP: 0018:ffffffff87007d80 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
> RAX: 0000000000000007 RBX: ffffffff8702cc40 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffffffff8702d48c
> RBP: fffffbfff0e05988 R08: ffffffff8702cc40 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000000 R14: ffffffff87e607c0 R15: 0000000000000000
>  cpuidle_idle_call kernel/sched/idle.c:154 [inline]
>  do_idle+0x3e0/0x500 kernel/sched/idle.c:269
>  cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361
>  start_kernel+0xe16/0xe5a init/main.c:998
>  secondary_startup_64+0xb6/0xc0 arch/x86/kernel/head_64.S:242
>
> The buggy address belongs to the page:
> page:ffffea000736a600 refcount:32769 mapcount:0 mapping:0000000000000000 index:0x0 compound_mapcount: 0
> flags: 0x200000000010000(head)
> raw: 0200000000010000 dead000000000100 dead000000000122 0000000000000000
> raw: 0000000000000000 0000000000000000 00008001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8881cda9ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff8881cda9ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff8881cdaa0000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                    ^
>  ffff8881cdaa0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8881cdaa0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches

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From 30f5f2182d562b60c35df6483c92c1bf62ed0ec8 Mon Sep 17 00:00:00 2001
From: Qiujun Huang <hqjagain@gmail.com>
Date: Thu, 26 Mar 2020 10:14:12 +0800
Subject: [PATCH 2/2] staging: wlan-ng: fix use-after-free Read in
 hfa384x_usbin_callback

Because the size of rxfrm->data is WLAN_DATA_MAXLEN(2312),so skblen
can't be more than that.

Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
---
 drivers/staging/wlan-ng/hfa384x_usb.c | 2 ++
 1 file changed, 2 insertions(+)
 mode change 100644 => 100755 drivers/staging/wlan-ng/hfa384x_usb.c

diff --git a/drivers/staging/wlan-ng/hfa384x_usb.c b/drivers/staging/wlan-ng/hfa384x_usb.c
old mode 100644
new mode 100755
index b71756ab0394..7fe64fcd385d
--- a/drivers/staging/wlan-ng/hfa384x_usb.c
+++ b/drivers/staging/wlan-ng/hfa384x_usb.c
@@ -3372,6 +3372,8 @@ static void hfa384x_int_rxmonitor(struct wlandevice *wlandev,
 	     WLAN_HDR_A4_LEN + WLAN_DATA_MAXLEN + WLAN_CRC_LEN)) {
 		pr_debug("overlen frm: len=%zd\n",
 			 skblen - sizeof(struct p80211_caphdr));
+
+		return;
 	}
 
 	skb = dev_alloc_skb(skblen);
-- 
2.17.1