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=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@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== 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 ================================================================== --- This bug is generated by a bot. 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