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BUG: KASAN: use-after-free in vkms_dumb_create+0x286/0x290 drivers/gpu/drm/vkms/vkms_gem.c:142
Read of size 8 at addr ffff888096acf910 by task syz-executor.1/15908

CPU: 0 PID: 15908 Comm: syz-executor.1 Not tainted 5.7.0-rc2-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+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382
 __kasan_report.cold+0x35/0x4d mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 vkms_dumb_create+0x286/0x290 drivers/gpu/drm/vkms/vkms_gem.c:142
 drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x220/0x2f0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x4c9/0x980 drivers/gpu/drm/drm_ioctl.c:887
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c829
Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4ca849fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e2d80 RCX: 000000000045c829
RDX: 0000000020000080 RSI: 00000000c02064b2 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000028b R14: 00000000004d3188 R15: 00007f4ca84a06d4

Allocated by task 15908:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc mm/kasan/common.c:495 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551
 __vkms_gem_create+0x44/0xf0 include/linux/slab.h:555
 vkms_gem_create drivers/gpu/drm/vkms/vkms_gem.c:111 [inline]
 vkms_gem_create drivers/gpu/drm/vkms/vkms_gem.c:100 [inline]
 vkms_dumb_create+0x110/0x290 drivers/gpu/drm/vkms/vkms_gem.c:138
 drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x220/0x2f0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x4c9/0x980 drivers/gpu/drm/drm_ioctl.c:887
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 15908:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 drm_gem_object_free+0xf0/0x1f0 drivers/gpu/drm/drm_gem.c:983
 kref_put include/linux/kref.h:65 [inline]
 drm_gem_object_put_unlocked drivers/gpu/drm/drm_gem.c:1017 [inline]
 drm_gem_object_put_unlocked+0x190/0x1c0 drivers/gpu/drm/drm_gem.c:1002
 vkms_gem_create drivers/gpu/drm/vkms/vkms_gem.c:116 [inline]
 vkms_gem_create drivers/gpu/drm/vkms/vkms_gem.c:100 [inline]
 vkms_dumb_create+0x14d/0x290 drivers/gpu/drm/vkms/vkms_gem.c:138
 drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x220/0x2f0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x4c9/0x980 drivers/gpu/drm/drm_ioctl.c:887
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff888096acf800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 272 bytes inside of
 1024-byte region [ffff888096acf800, ffff888096acfc00)
The buggy address belongs to the page:
page:ffffea00025ab3c0 refcount:1 mapcount:0 mapping:0000000040ff70c4 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002753448 ffff8880aa001850 ffff8880aa000c40
raw: 0000000000000000 ffff888096acf000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888096acf800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888096acf880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888096acf900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888096acf980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888096acfa00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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