syzbot

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BUG: KASAN: use-after-free in __ptr_ring_peek include/linux/ptr_ring.h:179 [inline]
BUG: KASAN: use-after-free in __ptr_ring_consume include/linux/ptr_ring.h:249 [inline]
BUG: KASAN: use-after-free in ptr_ring_consume include/linux/ptr_ring.h:269 [inline]
BUG: KASAN: use-after-free in skb_array_consume include/linux/skb_array.h:97 [inline]
BUG: KASAN: use-after-free in tun_ring_recv drivers/net/tun.c:1477 [inline]
BUG: KASAN: use-after-free in tun_do_read.part.42+0x1033/0x1250 drivers/net/tun.c:1514
Read of size 8 at addr ffff8801ac086600 by task syz-executor1/19532

CPU: 1 PID: 19532 Comm: syz-executor1 Not tainted 4.9.99-gc2f9bce #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801c370f9d8 ffffffff81eb0f09 ffffea0006b02000 ffff8801ac086600
 0000000000000000 ffff8801ac086600 1ffff1003994d0b9 ffff8801c370fa10
 ffffffff815652eb ffff8801ac086600 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81eb0f09>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0f09>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff815652eb>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff815656f5>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff815656f5>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff81539374>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff8280ebf3>] __ptr_ring_peek include/linux/ptr_ring.h:179 [inline]
 [<ffffffff8280ebf3>] __ptr_ring_consume include/linux/ptr_ring.h:249 [inline]
 [<ffffffff8280ebf3>] ptr_ring_consume include/linux/ptr_ring.h:269 [inline]
 [<ffffffff8280ebf3>] skb_array_consume include/linux/skb_array.h:97 [inline]
 [<ffffffff8280ebf3>] tun_ring_recv drivers/net/tun.c:1477 [inline]
 [<ffffffff8280ebf3>] tun_do_read.part.42+0x1033/0x1250 drivers/net/tun.c:1514
 [<ffffffff828105b1>] tun_do_read drivers/net/tun.c:1536 [inline]
 [<ffffffff828105b1>] tun_chr_read_iter+0x161/0x1f0 drivers/net/tun.c:1536
 [<ffffffff8156e8cd>] new_sync_read fs/read_write.c:439 [inline]
 [<ffffffff8156e8cd>] __vfs_read+0x3dd/0x570 fs/read_write.c:451
 [<ffffffff8156fdd0>] vfs_read+0x120/0x380 fs/read_write.c:472
 [<ffffffff81574215>] SYSC_pread64 fs/read_write.c:626 [inline]
 [<ffffffff81574215>] SyS_pread64+0x145/0x170 fs/read_write.c:613
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4653>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Allocated by task 19532:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:505
 set_track mm/kasan/kasan.c:517 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:609
 __kmalloc+0x11d/0x300 mm/slub.c:3741
 kmalloc_array include/linux/slab.h:582 [inline]
 kcalloc include/linux/slab.h:593 [inline]
 __ptr_ring_init_queue_alloc include/linux/ptr_ring.h:356 [inline]
 ptr_ring_init include/linux/ptr_ring.h:361 [inline]
 skb_array_init include/linux/skb_array.h:151 [inline]
 tun_attach+0x63c/0xa70 drivers/net/tun.c:665
 tun_set_iff drivers/net/tun.c:1842 [inline]
 __tun_chr_ioctl+0x2663/0x3450 drivers/net/tun.c:2051
 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2300
 vfs_ioctl fs/ioctl.c:43 [inline]
 file_ioctl fs/ioctl.c:493 [inline]
 do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 SYSC_ioctl fs/ioctl.c:694 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Freed by task 19570:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack+0x43/0xd0 mm/kasan/kasan.c:505
 set_track mm/kasan/kasan.c:517 [inline]
 kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:582
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kfree+0xfb/0x310 mm/slub.c:3878
 ptr_ring_cleanup include/linux/ptr_ring.h:483 [inline]
 skb_array_cleanup include/linux/skb_array.h:176 [inline]
 tun_cleanup_tx_array.part.39+0x16f/0x1f0 drivers/net/tun.c:531
 tun_cleanup_tx_array drivers/net/tun.c:530 [inline]
 tun_detach_all+0x394/0x7e0 drivers/net/tun.c:616
 tun_net_uninit+0x15/0x20 drivers/net/tun.c:825
 rollback_registered_many+0x684/0x920 net/core/dev.c:6846
 unregister_netdevice_many.part.106+0x1b/0x110 net/core/dev.c:7879
 unregister_netdevice_many+0x39/0x50 net/core/dev.c:7878
 rtnl_delete_link+0xdc/0x130 net/core/rtnetlink.c:2292
 rtnl_dellink+0x1e7/0x670 net/core/rtnetlink.c:2327
 rtnetlink_rcv_msg+0x49c/0x650 net/core/rtnetlink.c:4059
 netlink_rcv_skb+0x145/0x370 net/netlink/af_netlink.c:2356
 rtnetlink_rcv+0x2a/0x40 net/core/rtnetlink.c:4065
 netlink_unicast_kernel net/netlink/af_netlink.c:1278 [inline]
 netlink_unicast+0x4d8/0x6f0 net/netlink/af_netlink.c:1304
 netlink_sendmsg+0x78b/0xc10 net/netlink/af_netlink.c:1850
 sock_sendmsg_nosec net/socket.c:635 [inline]
 sock_sendmsg+0xcc/0x110 net/socket.c:645
 ___sys_sendmsg+0x6fc/0x840 net/socket.c:1969
 __sys_sendmsg+0xd9/0x190 net/socket.c:2003
 SYSC_sendmsg net/socket.c:2014 [inline]
 SyS_sendmsg+0x2d/0x50 net/socket.c:2010
 do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the object at ffff8801ac086600
 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 0 bytes inside of
 4096-byte region [ffff8801ac086600, ffff8801ac087600)
The buggy address belongs to the page:
page:ffffea0006b02000 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x8000000000004080(slab|head)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ac086500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801ac086580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801ac086600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801ac086680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801ac086700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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