(Sorry for the resend, I was in HTML mode earlier :S) Hi, I'm trying to get up to speed on USB kernel code. Sounds like dev->intf should have been set to NULL for the error path in ld_usb_probe() ? https://elixir.bootlin.com/linux/latest/source/drivers/usb/misc/ldusb.c#L666 On Fri, Aug 9, 2019 at 10:48 AM syzbot <syzbot+22ae4e3b9fcc8a5c153a@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: e96407b4 usb-fuzzer: main usb gadget fuzzer driver > git tree: https://github.com/google/kasan.git usb-fuzzer > console output: https://syzkaller.appspot.com/x/log.txt?x=1799392c600000 > kernel config: https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e > dashboard link: https://syzkaller.appspot.com/bug?extid=22ae4e3b9fcc8a5c153a > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1134c802600000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13278c4a600000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+22ae4e3b9fcc8a5c153a@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: use-after-free in atomic_read > include/asm-generic/atomic-instrumented.h:26 [inline] > BUG: KASAN: use-after-free in usb_kill_urb drivers/usb/core/urb.c:695 > [inline] > BUG: KASAN: use-after-free in usb_kill_urb+0x24b/0x2c0 > drivers/usb/core/urb.c:687 > Read of size 4 at addr ffff8881d635b110 by task syz-executor672/1999 > > CPU: 1 PID: 1999 Comm: syz-executor672 Not tainted 5.3.0-rc2+ #25 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0xca/0x13e lib/dump_stack.c:113 > print_address_description+0x6a/0x32c mm/kasan/report.c:351 > __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:482 > kasan_report+0xe/0x12 mm/kasan/common.c:612 > check_memory_region_inline mm/kasan/generic.c:185 [inline] > check_memory_region+0x128/0x190 mm/kasan/generic.c:192 > atomic_read include/asm-generic/atomic-instrumented.h:26 [inline] > usb_kill_urb drivers/usb/core/urb.c:695 [inline] > usb_kill_urb+0x24b/0x2c0 drivers/usb/core/urb.c:687 > ld_usb_abort_transfers+0xb7/0x1d0 drivers/usb/misc/ldusb.c:196 > ld_usb_release+0x19f/0x400 drivers/usb/misc/ldusb.c:406 > __fput+0x2d7/0x840 fs/file_table.c:280 > task_work_run+0x13f/0x1c0 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] > do_exit+0x8ef/0x2c50 kernel/exit.c:878 > do_group_exit+0x125/0x340 kernel/exit.c:982 > __do_sys_exit_group kernel/exit.c:993 [inline] > __se_sys_exit_group kernel/exit.c:991 [inline] > __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:991 > do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x440418 > Code: 00 00 be 3c 00 00 00 eb 19 66 0f 1f 84 00 00 00 00 00 48 89 d7 89 f0 > 0f 05 48 3d 00 f0 ff ff 77 21 f4 48 89 d7 44 89 c0 0f 05 <48> 3d 00 f0 ff > ff 76 e0 f7 d8 64 41 89 01 eb d8 0f 1f 84 00 00 00 > RSP: 002b:00007ffe884abf88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440418 > RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 > RBP: 00000000004bff50 R08: 00000000000000e7 R09: ffffffffffffffd0 > R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000001 > R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 > > Allocated by task 22: > save_stack+0x1b/0x80 mm/kasan/common.c:69 > set_track mm/kasan/common.c:77 [inline] > __kasan_kmalloc mm/kasan/common.c:487 [inline] > __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:460 > kmalloc include/linux/slab.h:557 [inline] > usb_alloc_urb+0x65/0xb0 drivers/usb/core/urb.c:73 > ld_usb_probe+0x3e1/0xa65 drivers/usb/misc/ldusb.c:708 > usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361 > really_probe+0x281/0x650 drivers/base/dd.c:548 > driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709 > __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816 > bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454 > __device_attach+0x217/0x360 drivers/base/dd.c:882 > bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514 > device_add+0xae6/0x16f0 drivers/base/core.c:2114 > usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023 > generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210 > usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266 > really_probe+0x281/0x650 drivers/base/dd.c:548 > driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709 > __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816 > bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454 > __device_attach+0x217/0x360 drivers/base/dd.c:882 > bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514 > device_add+0xae6/0x16f0 drivers/base/core.c:2114 > usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536 > hub_port_connect drivers/usb/core/hub.c:5098 [inline] > hub_port_connect_change drivers/usb/core/hub.c:5213 [inline] > port_event drivers/usb/core/hub.c:5359 [inline] > hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441 > process_one_work+0x92b/0x1530 kernel/workqueue.c:2269 > worker_thread+0x96/0xe20 kernel/workqueue.c:2415 > kthread+0x318/0x420 kernel/kthread.c:255 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > Freed by task 22: > save_stack+0x1b/0x80 mm/kasan/common.c:69 > set_track mm/kasan/common.c:77 [inline] > __kasan_slab_free+0x130/0x180 mm/kasan/common.c:449 > slab_free_hook mm/slub.c:1423 [inline] > slab_free_freelist_hook mm/slub.c:1470 [inline] > slab_free mm/slub.c:3012 [inline] > kfree+0xe4/0x2f0 mm/slub.c:3953 > urb_destroy drivers/usb/core/urb.c:26 [inline] > kref_put include/linux/kref.h:65 [inline] > usb_free_urb.part.0+0x7a/0xc0 drivers/usb/core/urb.c:95 > usb_free_urb+0x1b/0x30 drivers/usb/core/urb.c:94 > ld_usb_delete+0x3f/0x130 drivers/usb/misc/ldusb.c:211 > ld_usb_probe+0x728/0xa65 drivers/usb/misc/ldusb.c:744 > usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361 > really_probe+0x281/0x650 drivers/base/dd.c:548 > driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709 > __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816 > bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454 > __device_attach+0x217/0x360 drivers/base/dd.c:882 > bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514 > device_add+0xae6/0x16f0 drivers/base/core.c:2114 > usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023 > generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210 > usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266 > really_probe+0x281/0x650 drivers/base/dd.c:548 > driver_probe_device+0x101/0x1b0 drivers/base/dd.c:709 > __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:816 > bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454 > __device_attach+0x217/0x360 drivers/base/dd.c:882 > bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514 > device_add+0xae6/0x16f0 drivers/base/core.c:2114 > usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536 > hub_port_connect drivers/usb/core/hub.c:5098 [inline] > hub_port_connect_change drivers/usb/core/hub.c:5213 [inline] > port_event drivers/usb/core/hub.c:5359 [inline] > hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441 > process_one_work+0x92b/0x1530 kernel/workqueue.c:2269 > worker_thread+0x96/0xe20 kernel/workqueue.c:2415 > 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 ffff8881d635b100 > which belongs to the cache kmalloc-192 of size 192 > The buggy address is located 16 bytes inside of > 192-byte region [ffff8881d635b100, ffff8881d635b1c0) > The buggy address belongs to the page: > page:ffffea000758d6c0 refcount:1 mapcount:0 mapping:ffff8881da002a00 > index:0x0 > flags: 0x200000000000200(slab) > raw: 0200000000000200 dead000000000100 dead000000000122 ffff8881da002a00 > raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8881d635b000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8881d635b080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > > ffff8881d635b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff8881d635b180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > ffff8881d635b200: 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@xxxxxxxxxxxxxxxx. > > 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
