================================================================== BUG: KASAN: use-after-free in vgem_gem_dumb_create+0x178/0x320 drivers/gpu/drm/vgem/vgem_drv.c:221 Read of size 8 at addr ffff88809f175908 by task syz-executor.0/21515 CPU: 0 PID: 21515 Comm: syz-executor.0 Not tainted 5.5.0-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+0x1fb/0x318 lib/dump_stack.c:118 print_address_description+0x74/0x5c0 mm/kasan/report.c:374 __kasan_report+0x149/0x1c0 mm/kasan/report.c:506 kasan_report+0x26/0x50 mm/kasan/common.c:639 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 vgem_gem_dumb_create+0x178/0x320 drivers/gpu/drm/vgem/vgem_drv.c:221 drm_mode_create_dumb drivers/gpu/drm/drm_dumb_buffers.c:94 [inline] drm_mode_create_dumb_ioctl+0x22e/0x2a0 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x2cf/0x410 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x52f/0x890 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:747 [inline] __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl+0x113/0x190 fs/ioctl.c:754 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:754 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b399 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:00007f3d69456c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f3d694576d4 RCX: 000000000045b399 RDX: 0000000020000000 RSI: 00000000c02064b2 RDI: 0000000000000003 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000285 R14: 00000000004d1568 R15: 000000000075bfd4 Allocated by task 21515: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:513 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 kmem_cache_alloc_trace+0x221/0x2f0 mm/slab.c:3551 kmalloc include/linux/slab.h:556 [inline] kzalloc include/linux/slab.h:670 [inline] __vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:165 [inline] vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:194 [inline] vgem_gem_dumb_create+0xd8/0x320 drivers/gpu/drm/vgem/vgem_drv.c:217 drm_mode_create_dumb drivers/gpu/drm/drm_dumb_buffers.c:94 [inline] drm_mode_create_dumb_ioctl+0x22e/0x2a0 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x2cf/0x410 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x52f/0x890 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:747 [inline] __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl+0x113/0x190 fs/ioctl.c:754 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:754 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 21515: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:335 [inline] __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:474 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483 __cache_free mm/slab.c:3426 [inline] kfree+0x10d/0x220 mm/slab.c:3757 vgem_gem_free_object+0xb5/0xc0 drivers/gpu/drm/vgem/vgem_drv.c:68 drm_gem_object_free drivers/gpu/drm/drm_gem.c:983 [inline] kref_put include/linux/kref.h:65 [inline] drm_gem_object_put_unlocked+0x33a/0x4b0 drivers/gpu/drm/drm_gem.c:1017 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline] vgem_gem_dumb_create+0x265/0x320 drivers/gpu/drm/vgem/vgem_drv.c:217 drm_mode_create_dumb drivers/gpu/drm/drm_dumb_buffers.c:94 [inline] drm_mode_create_dumb_ioctl+0x22e/0x2a0 drivers/gpu/drm/drm_dumb_buffers.c:100 drm_ioctl_kernel+0x2cf/0x410 drivers/gpu/drm/drm_ioctl.c:786 drm_ioctl+0x52f/0x890 drivers/gpu/drm/drm_ioctl.c:886 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl fs/ioctl.c:747 [inline] __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl+0x113/0x190 fs/ioctl.c:754 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:754 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff88809f175800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 264 bytes inside of 1024-byte region [ffff88809f175800, ffff88809f175c00) The buggy address belongs to the page: page:ffffea00027c5d40 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0 raw: 00fffe0000000200 ffffea0002613508 ffffea00027c0f88 ffff8880aa400c40 raw: 0000000000000000 ffff88809f175000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809f175800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809f175880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88809f175900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88809f175980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809f175a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================