IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
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BUG: KASAN: use-after-free in vgem_gem_dumb_create+0x200/0x210 drivers/gpu/drm/vgem/vgem_drv.c:215
Read of size 8 at addr ffff8880a0189900 by task syz-executor.0/13797

CPU: 1 PID: 13797 Comm: syz-executor.0 Not tainted 4.14.174-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+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 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+0xa9/0x2ae mm/kasan/report.c:393
 vgem_gem_dumb_create+0x200/0x210 drivers/gpu/drm/vgem/vgem_drv.c:215
 drm_mode_create_dumb_ioctl+0x221/0x2b0 drivers/gpu/drm/drm_dumb_buffers.c:92
 drm_ioctl_kernel+0x150/0x200 drivers/gpu/drm/drm_ioctl.c:736
 drm_ioctl+0x416/0x880 drivers/gpu/drm/drm_ioctl.c:836
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007f1b97ee2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1b97ee36d4 RCX: 000000000045c849
RDX: 0000000020000000 RSI: 00000000c02064b2 RDI: 0000000000000004
RBP: 000000000076bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000289 R14: 00000000004d30a0 R15: 000000000076bfac

Allocated by task 13797:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 kmem_cache_alloc_trace+0x14d/0x7b0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 __vgem_gem_create+0x44/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:159
 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:188 [inline]
 vgem_gem_dumb_create+0xc5/0x210 drivers/gpu/drm/vgem/vgem_drv.c:211
 drm_mode_create_dumb_ioctl+0x221/0x2b0 drivers/gpu/drm/drm_dumb_buffers.c:92
 drm_ioctl_kernel+0x150/0x200 drivers/gpu/drm/drm_ioctl.c:736
 drm_ioctl+0x416/0x880 drivers/gpu/drm/drm_ioctl.c:836
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 13797:
 save_stack+0x32/0xa0 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+0xcb/0x260 mm/slab.c:3815
 drm_gem_object_free+0x8f/0x150 drivers/gpu/drm/drm_gem.c:838
 kref_put include/linux/kref.h:70 [inline]
 drm_gem_object_put_unlocked+0x12c/0x160 drivers/gpu/drm/drm_gem.c:867
 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:193 [inline]
 vgem_gem_dumb_create+0xf2/0x210 drivers/gpu/drm/vgem/vgem_drv.c:211
 drm_mode_create_dumb_ioctl+0x221/0x2b0 drivers/gpu/drm/drm_dumb_buffers.c:92
 drm_ioctl_kernel+0x150/0x200 drivers/gpu/drm/drm_ioctl.c:736
 drm_ioctl+0x416/0x880 drivers/gpu/drm/drm_ioctl.c:836
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8880a0189800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 256 bytes inside of
 512-byte region [ffff8880a0189800, ffff8880a0189a00)
The buggy address belongs to the page:
page:ffffea0002806240 count:1 mapcount:0 mapping:ffff8880a0189080 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880a0189080 0000000000000000 0000000100000006
raw: ffffea00020d1da0 ffffea000283d4e0 ffff88812fe56940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a0189800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a0189880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a0189900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8880a0189980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a0189a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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