Message-ID: <CAAeHK+wig7mLNDPRwMcrRxd+=trQT3oHnYpscgWQLs5NWW_=WQ@mail.gmail.com>
Date:   Thu, 26 Mar 2020 14:25:08 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Hillf Danton <hdanton@...a.com>
Cc:     syzbot <syzbot+b894396e6110e1df38c4@...kaller.appspotmail.com>,
        ath9k-devel@....qualcomm.com,
        "David S. Miller" <davem@...emloft.net>,
        Kalle Valo <kvalo@...eaurora.org>,
        LKML <linux-kernel@...r.kernel.org>,
        USB list <linux-usb@...r.kernel.org>,
        linux-wireless@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: KASAN: use-after-free Read in hif_usb_regout_cb

On Thu, Mar 26, 2020 at 1:42 PM Hillf Danton <hdanton@...a.com> wrote:
>
>
> On Thu, 26 Mar 2020 04:34:16 -0700
> > 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=13ee4d4be00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=5d64370c438bc60
> > dashboard link: https://syzkaller.appspot.com/bug?extid=b894396e6110e1df38c4
> > 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+b894396e6110e1df38c4@...kaller.appspotmail.com
> >
> > ==================================================================
> > BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
> > BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:134 [inline]
> > BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:1042 [inline]
> > BUG: KASAN: use-after-free in kfree_skb+0x32/0x3d0 net/core/skbuff.c:692
> > Read of size 4 at addr ffff8881d6816494 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
> >  atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
> >  refcount_read include/linux/refcount.h:134 [inline]
> >  skb_unref include/linux/skbuff.h:1042 [inline]
> >  kfree_skb+0x32/0x3d0 net/core/skbuff.c:692
> >  hif_usb_regout_cb+0x14c/0x1b0 drivers/net/wireless/ath/ath9k/hif_usb.c:97
> >  __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
> >
> > Allocated by task 3135:
> >  save_stack+0x1b/0x80 mm/kasan/common.c:72
> >  set_track mm/kasan/common.c:80 [inline]
> >  __kasan_kmalloc mm/kasan/common.c:515 [inline]
> >  __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488
> >  slab_post_alloc_hook mm/slab.h:584 [inline]
> >  slab_alloc_node mm/slub.c:2778 [inline]
> >  kmem_cache_alloc_node+0xdc/0x330 mm/slub.c:2814
> >  __alloc_skb+0xba/0x5a0 net/core/skbuff.c:198
> >  alloc_skb include/linux/skbuff.h:1081 [inline]
> >  htc_connect_service+0x2cc/0x840 drivers/net/wireless/ath/ath9k/htc_hst.c:257
> >  ath9k_wmi_connect+0xd2/0x1a0 drivers/net/wireless/ath/ath9k/wmi.c:265
> >  ath9k_init_htc_services.constprop.0+0xb4/0x650 drivers/net/wireless/ath/ath9k/htc_drv_init.c:146
> >  ath9k_htc_probe_device+0x25a/0x1d80 drivers/net/wireless/ath/ath9k/htc_drv_init.c:959
> >  ath9k_htc_hw_init+0x31/0x60 drivers/net/wireless/ath/ath9k/htc_hst.c:501
> >  ath9k_hif_usb_firmware_cb+0x26b/0x500 drivers/net/wireless/ath/ath9k/hif_usb.c:1187
> >  request_firmware_work_func+0x126/0x242 drivers/base/firmware_loader/main.c:976
> >  process_one_work+0x94b/0x1620 kernel/workqueue.c:2264
> >  worker_thread+0x96/0xe20 kernel/workqueue.c:2410
> >  kthread+0x318/0x420 kernel/kthread.c:255
> >  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
> >
> > Freed by task 3135:
> >  save_stack+0x1b/0x80 mm/kasan/common.c:72
> >  set_track mm/kasan/common.c:80 [inline]
> >  kasan_set_free_info mm/kasan/common.c:337 [inline]
> >  __kasan_slab_free+0x117/0x160 mm/kasan/common.c:476
> >  slab_free_hook mm/slub.c:1444 [inline]
> >  slab_free_freelist_hook mm/slub.c:1477 [inline]
> >  slab_free mm/slub.c:3024 [inline]
> >  kmem_cache_free+0x9b/0x360 mm/slub.c:3040
> >  kfree_skbmem net/core/skbuff.c:622 [inline]
> >  kfree_skbmem+0xef/0x1b0 net/core/skbuff.c:616
> >  __kfree_skb net/core/skbuff.c:679 [inline]
> >  kfree_skb net/core/skbuff.c:696 [inline]
> >  kfree_skb+0x102/0x3d0 net/core/skbuff.c:690
> >  htc_connect_service.cold+0xa9/0x109 drivers/net/wireless/ath/ath9k/htc_hst.c:282
> >  ath9k_wmi_connect+0xd2/0x1a0 drivers/net/wireless/ath/ath9k/wmi.c:265
> >  ath9k_init_htc_services.constprop.0+0xb4/0x650 drivers/net/wireless/ath/ath9k/htc_drv_init.c:146
> >  ath9k_htc_probe_device+0x25a/0x1d80 drivers/net/wireless/ath/ath9k/htc_drv_init.c:959
> >  ath9k_htc_hw_init+0x31/0x60 drivers/net/wireless/ath/ath9k/htc_hst.c:501
> >  ath9k_hif_usb_firmware_cb+0x26b/0x500 drivers/net/wireless/ath/ath9k/hif_usb.c:1187
> >  request_firmware_work_func+0x126/0x242 drivers/base/firmware_loader/main.c:976
> >  process_one_work+0x94b/0x1620 kernel/workqueue.c:2264
> >  worker_thread+0x96/0xe20 kernel/workqueue.c:2410
> >  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 ffff8881d68163c0
> >  which belongs to the cache skbuff_head_cache of size 224
> > The buggy address is located 212 bytes inside of
> >  224-byte region [ffff8881d68163c0, ffff8881d68164a0)
> > The buggy address belongs to the page:
> > page:ffffea00075a0580 refcount:1 mapcount:0 mapping:ffff8881da16b400 index:0x0
> > flags: 0x200000000000200(slab)
> > raw: 0200000000000200 ffffea00072b75c0 0000000300000002 ffff8881da16b400
> > raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> >
> > Memory state around the buggy address:
> >  ffff8881d6816380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> >  ffff8881d6816400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > >ffff8881d6816480: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
> >                          ^
> >  ffff8881d6816500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >  ffff8881d6816580: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
> > ==================================================================
>
> Trust the usb driver to do its work with skb cared after a successful
> send, even in case of timeout.
>
> --- a/drivers/net/wireless/ath/ath9k/htc_hst.c
> +++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
> @@ -279,7 +279,6 @@ int htc_connect_service(struct htc_targe
>         if (!time_left) {
>                 dev_err(target->dev, "Service connection timeout for: %d\n",
>                         service_connreq->service_id);
> -               kfree_skb(skb);
>                 return -ETIMEDOUT;
>         }

Hi Hillf,

I think this is the 50th patch I see from you sent as a reply to a
syzbot report without a clear indication what to do with it. You
either need to issue a syz test command if you want your patch to be
tested by syzbot, or send the patch property if you want to get it
picked up by maintainers. I really appreciate you looking at the
reports and working on fixing the bugs, but just sending patches as
replies is pointless.

Thanks!

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