================================================================== BUG: KASAN: use-after-free in vgem_gem_dumb_create+0x22c/0x240 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/vgem/vgem_drv.c:214 Read of size 8 at addr ffff8880a4c02680 by task syz-executor059/8116 CPU: 1 PID: 8116 Comm: syz-executor059 Not tainted 4.19.172-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack syzkaller/managers/linux-4-19/kernel/lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef syzkaller/managers/linux-4-19/kernel/lib/dump_stack.c:118 print_address_description.cold+0x54/0x219 syzkaller/managers/linux-4-19/kernel/mm/kasan/report.c:256 kasan_report_error.cold+0x8a/0x1b9 syzkaller/managers/linux-4-19/kernel/mm/kasan/report.c:354 kasan_report syzkaller/managers/linux-4-19/kernel/mm/kasan/report.c:412 [inline] __asan_report_load8_noabort+0x88/0x90 syzkaller/managers/linux-4-19/kernel/mm/kasan/report.c:433 vgem_gem_dumb_create+0x22c/0x240 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/vgem/vgem_drv.c:214 drm_mode_create_dumb+0x27c/0x300 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_dumb_buffers.c:92 drm_ioctl_kernel+0x208/0x2a0 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_ioctl.c:757 drm_ioctl+0x507/0x9c0 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_ioctl.c:857 vfs_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:46 [inline] file_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:501 [inline] do_vfs_ioctl+0xcdb/0x12e0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:688 ksys_ioctl+0x9b/0xc0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:705 __do_sys_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:712 [inline] __se_sys_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6f/0xb0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:710 do_syscall_64+0xf9/0x620 syzkaller/managers/linux-4-19/kernel/arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x44a579 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fd6aff2e1f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004cb4e8 RCX: 000000000044a579 RDX: 00000000200000c0 RSI: 00000000c02064b2 RDI: 0000000000000004 RBP: 00000000004cb4e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cb4ec R13: 00007ffde95653df R14: 00007fd6aff2e300 R15: 0000000000022000 Allocated by task 8116: kmem_cache_alloc_trace+0x12f/0x380 syzkaller/managers/linux-4-19/kernel/mm/slab.c:3625 kmalloc syzkaller/managers/linux-4-19/kernel/./include/linux/slab.h:515 [inline] kzalloc syzkaller/managers/linux-4-19/kernel/./include/linux/slab.h:709 [inline] __vgem_gem_create+0x44/0xf0 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/vgem/vgem_drv.c:158 vgem_gem_create syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/vgem/vgem_drv.c:187 [inline] vgem_gem_dumb_create+0xcf/0x240 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/vgem/vgem_drv.c:210 drm_mode_create_dumb+0x27c/0x300 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_dumb_buffers.c:92 drm_ioctl_kernel+0x208/0x2a0 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_ioctl.c:757 drm_ioctl+0x507/0x9c0 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_ioctl.c:857 vfs_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:46 [inline] file_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:501 [inline] do_vfs_ioctl+0xcdb/0x12e0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:688 ksys_ioctl+0x9b/0xc0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:705 __do_sys_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:712 [inline] __se_sys_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6f/0xb0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:710 do_syscall_64+0xf9/0x620 syzkaller/managers/linux-4-19/kernel/arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 8116: __cache_free syzkaller/managers/linux-4-19/kernel/mm/slab.c:3503 [inline] kfree+0xcc/0x210 syzkaller/managers/linux-4-19/kernel/mm/slab.c:3822 drm_gem_object_free+0x91/0x1c0 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_gem.c:837 kref_put syzkaller/managers/linux-4-19/kernel/./include/linux/kref.h:70 [inline] drm_gem_object_put_unlocked+0xd1/0x180 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_gem.c:866 vgem_gem_create syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/vgem/vgem_drv.c:192 [inline] vgem_gem_dumb_create+0x10c/0x240 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/vgem/vgem_drv.c:210 drm_mode_create_dumb+0x27c/0x300 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_dumb_buffers.c:92 drm_ioctl_kernel+0x208/0x2a0 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_ioctl.c:757 drm_ioctl+0x507/0x9c0 syzkaller/managers/linux-4-19/kernel/drivers/gpu/drm/drm_ioctl.c:857 vfs_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:46 [inline] file_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:501 [inline] do_vfs_ioctl+0xcdb/0x12e0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:688 ksys_ioctl+0x9b/0xc0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:705 __do_sys_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:712 [inline] __se_sys_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6f/0xb0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:710 do_syscall_64+0xf9/0x620 syzkaller/managers/linux-4-19/kernel/arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880a4c02580 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 256 bytes inside of 512-byte region [ffff8880a4c02580, ffff8880a4c02780) The buggy address belongs to the page: page:ffffea0002930080 count:1 mapcount:0 mapping:ffff88813bff0940 index:0x0 flags: 0xfff00000000100(slab) raw: 00fff00000000100 ffffea00029301c8 ffffea000294dc48 ffff88813bff0940 raw: 0000000000000000 ffff8880a4c02080 0000000100000006 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a4c02580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a4c02600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a4c02680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a4c02700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a4c02780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================