batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
==================================================================
BUG: KASAN: use-after-free in vgem_gem_dumb_create+0x20c/0x220 drivers/gpu/drm/vgem/vgem_drv.c:215
Read of size 8 at addr ffff88809bb666c0 by task syz-executor.0/9878

CPU: 1 PID: 9878 Comm: syz-executor.0 Not tainted 4.14.169-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x142/0x197 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 vgem_gem_dumb_create+0x20c/0x220 drivers/gpu/drm/vgem/vgem_drv.c:215
 drm_mode_create_dumb_ioctl+0x22c/0x2b0 drivers/gpu/drm/drm_dumb_buffers.c:92
 drm_ioctl_kernel+0x154/0x210 drivers/gpu/drm/drm_ioctl.c:736
 drm_ioctl+0x493/0x940 drivers/gpu/drm/drm_ioctl.c:836
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45b349
RSP: 002b:00007faf00514c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007faf005156d4 RCX: 000000000045b349
RDX: 0000000020000180 RSI: 00000000c02064b2 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000285 R14: 00000000004d14d0 R15: 000000000075bf2c

Allocated by task 9878:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 kmem_cache_alloc_trace+0x152/0x790 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 __vgem_gem_create+0x49/0xf0 drivers/gpu/drm/vgem/vgem_drv.c:159
 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:188 [inline]
 vgem_gem_dumb_create+0xcd/0x220 drivers/gpu/drm/vgem/vgem_drv.c:211
 drm_mode_create_dumb_ioctl+0x22c/0x2b0 drivers/gpu/drm/drm_dumb_buffers.c:92
 drm_ioctl_kernel+0x154/0x210 drivers/gpu/drm/drm_ioctl.c:736
 drm_ioctl+0x493/0x940 drivers/gpu/drm/drm_ioctl.c:836
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 9878:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcc/0x270 mm/slab.c:3815
 vgem_gem_free_object+0xbe/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:61
 drm_gem_object_free+0x94/0x150 drivers/gpu/drm/drm_gem.c:838
 kref_put include/linux/kref.h:70 [inline]
 drm_gem_object_put_unlocked+0x12b/0x160 drivers/gpu/drm/drm_gem.c:867
 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:193 [inline]
 vgem_gem_dumb_create+0xfb/0x220 drivers/gpu/drm/vgem/vgem_drv.c:211
 drm_mode_create_dumb_ioctl+0x22c/0x2b0 drivers/gpu/drm/drm_dumb_buffers.c:92
 drm_ioctl_kernel+0x154/0x210 drivers/gpu/drm/drm_ioctl.c:736
 drm_ioctl+0x493/0x940 drivers/gpu/drm/drm_ioctl.c:836
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88809bb665c0
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 256 bytes inside of
 512-byte region [ffff88809bb665c0, ffff88809bb667c0)
The buggy address belongs to the page:
page:ffffea00026ed980 count:1 mapcount:0 mapping:ffff88809bb660c0 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff88809bb660c0 0000000000000000 0000000100000006
raw: ffffea0002297fa0 ffffea00026cd6a0 ffff8880aa800940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809bb66580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff88809bb66600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809bb66680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88809bb66700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809bb66780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================