IPv6: ADDRCONF(NETDEV_UP): vxcan0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready
==================================================================
BUG: KASAN: use-after-free in sl_sync drivers/net/slip/slip.c:725 [inline]
BUG: KASAN: use-after-free in slip_open+0xd87/0x10b4 drivers/net/slip/slip.c:801
Read of size 8 at addr ffff88808675f408 by task syz-executor.2/6943

CPU: 1 PID: 6943 Comm: syz-executor.2 Not tainted 4.19.84-syzkaller #0
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+0x123/0x177 lib/dump_stack.c:118
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 sl_sync drivers/net/slip/slip.c:725 [inline]
 slip_open+0xd87/0x10b4 drivers/net/slip/slip.c:801
 tty_ldisc_open.isra.3+0x65/0xa0 drivers/tty/tty_ldisc.c:462
 tty_set_ldisc+0x252/0x5b0 drivers/tty/tty_ldisc.c:587
 tiocsetd drivers/tty/tty_io.c:2359 [inline]
 tty_ioctl+0x31e/0x1290 drivers/tty/tty_io.c:2603
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688
 ksys_ioctl+0x62/0x90 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a639
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fadf16d7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fadf16d7c90 RCX: 000000000045a639
RDX: 00000000200003c0 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fadf16d86d4
R13: 00000000004c52b4 R14: 00000000004da170 R15: 0000000000000004

Allocated by task 6938:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc_node mm/slab.c:3689 [inline]
 __kmalloc_node+0x50/0x70 mm/slab.c:3696
 kmalloc_node include/linux/slab.h:557 [inline]
 kvmalloc_node+0x68/0x70 mm/util.c:423
 kvmalloc include/linux/mm.h:577 [inline]
 kvzalloc include/linux/mm.h:585 [inline]
 alloc_netdev_mqs+0x5d/0xc00 net/core/dev.c:8945
 sl_alloc drivers/net/slip/slip.c:751 [inline]
 slip_open+0x300/0x10b4 drivers/net/slip/slip.c:812
 tty_ldisc_open.isra.3+0x65/0xa0 drivers/tty/tty_ldisc.c:462
 tty_set_ldisc+0x252/0x5b0 drivers/tty/tty_ldisc.c:587
 tiocsetd drivers/tty/tty_io.c:2359 [inline]
 tty_ioctl+0x31e/0x1290 drivers/tty/tty_io.c:2603
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688
 ksys_ioctl+0x62/0x90 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6938:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcf/0x220 mm/slab.c:3822
 kvfree+0x2c/0x30 mm/util.c:452
 netdev_freemem net/core/dev.c:8899 [inline]
 free_netdev+0x312/0x3d0 net/core/dev.c:9048
 slip_open+0xb61/0x10b4 drivers/net/slip/slip.c:858
 tty_ldisc_open.isra.3+0x65/0xa0 drivers/tty/tty_ldisc.c:462
 tty_set_ldisc+0x252/0x5b0 drivers/tty/tty_ldisc.c:587
 tiocsetd drivers/tty/tty_io.c:2359 [inline]
 tty_ioctl+0x31e/0x1290 drivers/tty/tty_io.c:2603
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688
 ksys_ioctl+0x62/0x90 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88808675e940
 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 2760 bytes inside of
 4096-byte region [ffff88808675e940, ffff88808675f940)
The buggy address belongs to the page:
page:ffffea000219d780 count:1 mapcount:0 mapping:ffff88812c35edc0 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)
raw: 01fffc0000008100 ffffea0002201488 ffffea000219cb08 ffff88812c35edc0
raw: 0000000000000000 ffff88808675e940 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808675f300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808675f380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88808675f400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88808675f480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808675f500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================