Hello, syzbot found the following issue on: HEAD commit: 03275585cabd afs: Fix accidental truncation when storing d.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=16db258ca80000 kernel config: https://syzkaller.appspot.com/x/.config?x=d576750da57ebbb5 dashboard link: https://syzkaller.appspot.com/bug?extid=380dcf72caf0b5ef5537 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-03275585.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/6d035553cd50/vmlinux-03275585.xz kernel image: https://storage.googleapis.com/syzbot-assets/2fd7f855c25e/bzImage-03275585.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+380dcf72caf0b5ef5537@xxxxxxxxxxxxxxxxxxxxxxxxx BUG: KASAN: slab-use-after-free in drm_atomic_helper_wait_for_vblanks.part.0+0x77a/0x860 drivers/gpu/drm/drm_atomic_helper.c:1650 Read of size 1 at addr ffff888023f61009 by task kworker/u17:6/4248 CPU: 3 PID: 4248 Comm: kworker/u17:6 Not tainted 6.4.0-syzkaller-11472-g03275585cabd #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Workqueue: events_unbound commit_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:364 print_report mm/kasan/report.c:475 [inline] kasan_report+0x11d/0x130 mm/kasan/report.c:588 drm_atomic_helper_wait_for_vblanks.part.0+0x77a/0x860 drivers/gpu/drm/drm_atomic_helper.c:1650 drm_atomic_helper_wait_for_vblanks drivers/gpu/drm/drm_atomic_helper.c:1646 [inline] drm_atomic_helper_commit_tail+0xc7/0xf0 drivers/gpu/drm/drm_atomic_helper.c:1746 commit_tail+0x32d/0x420 drivers/gpu/drm/drm_atomic_helper.c:1823 process_one_work+0xa34/0x16f0 kernel/workqueue.c:2597 worker_thread+0x67d/0x10c0 kernel/workqueue.c:2748 kthread+0x344/0x440 kernel/kthread.c:389 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 </TASK> Allocated by task 28853: kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] ____kasan_kmalloc mm/kasan/common.c:333 [inline] __kasan_kmalloc+0xa2/0xb0 mm/kasan/common.c:383 kmalloc include/linux/slab.h:579 [inline] drm_atomic_helper_crtc_duplicate_state+0x6f/0xc0 drivers/gpu/drm/drm_atomic_state_helper.c:177 drm_simple_kms_crtc_duplicate_state+0x8b/0xb0 drivers/gpu/drm/drm_simple_kms_helper.c:166 drm_atomic_get_crtc_state+0x179/0x470 drivers/gpu/drm/drm_atomic.c:353 page_flip_common+0x57/0x310 drivers/gpu/drm/drm_atomic_helper.c:3589 drm_atomic_helper_page_flip+0xb8/0x190 drivers/gpu/drm/drm_atomic_helper.c:3650 drm_mode_page_flip_ioctl+0xf20/0x12a0 drivers/gpu/drm/drm_plane.c:1373 drm_ioctl_kernel+0x281/0x4e0 drivers/gpu/drm/drm_ioctl.c:788 drm_ioctl+0x577/0xb30 drivers/gpu/drm/drm_ioctl.c:891 drm_compat_ioctl+0x375/0x4b0 drivers/gpu/drm/drm_ioc32.c:988 __do_compat_sys_ioctl+0x25b/0x2b0 fs/ioctl.c:968 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 Freed by task 28850: kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:521 ____kasan_slab_free mm/kasan/common.c:236 [inline] ____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200 kasan_slab_free include/linux/kasan.h:162 [inline] slab_free_hook mm/slub.c:1792 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1818 slab_free mm/slub.c:3801 [inline] __kmem_cache_free+0xb8/0x2d0 mm/slub.c:3814 drm_simple_kms_crtc_destroy_state+0x8c/0xb0 drivers/gpu/drm/drm_simple_kms_helper.c:177 drm_atomic_state_default_clear+0x3a7/0xdd0 drivers/gpu/drm/drm_atomic.c:219 drm_atomic_state_clear drivers/gpu/drm/drm_atomic.c:288 [inline] __drm_atomic_state_free+0x176/0x2b0 drivers/gpu/drm/drm_atomic.c:304 kref_put include/linux/kref.h:65 [inline] drm_atomic_state_put include/drm/drm_atomic.h:490 [inline] drm_client_modeset_commit_atomic+0x6b0/0x7e0 drivers/gpu/drm/drm_client_modeset.c:1051 drm_client_modeset_commit_locked+0x149/0x580 drivers/gpu/drm/drm_client_modeset.c:1148 drm_client_modeset_commit+0x51/0x80 drivers/gpu/drm/drm_client_modeset.c:1174 __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:251 [inline] __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:230 [inline] drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:278 [inline] drm_fb_helper_lastclose+0xc5/0x170 drivers/gpu/drm/drm_fb_helper.c:2005 drm_fbdev_generic_client_restore+0x2c/0x40 drivers/gpu/drm/drm_fbdev_generic.c:259 drm_client_dev_restore+0x188/0x290 drivers/gpu/drm/drm_client.c:236 drm_release+0x40d/0x4f0 drivers/gpu/drm/drm_file.c:497 __fput+0x40c/0xad0 fs/file_table.c:384 task_work_run+0x16f/0x270 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x210/0x240 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297 __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 Last potentially related work creation: kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 __kasan_record_aux_stack+0xb9/0xd0 mm/kasan/generic.c:491 insert_work+0x48/0x360 kernel/workqueue.c:1553 __queue_work+0x625/0x1120 kernel/workqueue.c:1714 call_timer_fn+0x1a0/0x580 kernel/time/timer.c:1700 expire_timers+0xbc/0x4b0 kernel/time/timer.c:1746 __run_timers kernel/time/timer.c:2022 [inline] __run_timers kernel/time/timer.c:1995 [inline] run_timer_softirq+0x326/0x910 kernel/time/timer.c:2035 __do_softirq+0x1d4/0x905 kernel/softirq.c:553 Second to last potentially related work creation: kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 __kasan_record_aux_stack+0xb9/0xd0 mm/kasan/generic.c:491 insert_work+0x48/0x360 kernel/workqueue.c:1553 __queue_work+0x625/0x1120 kernel/workqueue.c:1714 call_timer_fn+0x1a0/0x580 kernel/time/timer.c:1700 expire_timers+0xbc/0x4b0 kernel/time/timer.c:1746 __run_timers kernel/time/timer.c:2022 [inline] __run_timers kernel/time/timer.c:1995 [inline] run_timer_softirq+0x326/0x910 kernel/time/timer.c:2035 __do_softirq+0x1d4/0x905 kernel/softirq.c:553 The buggy address belongs to the object at ffff888023f61000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 9 bytes inside of freed 512-byte region [ffff888023f61000, ffff888023f61200) The buggy address belongs to the physical page: page:ffffea00008fd800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x23f60 head:ffffea00008fd800 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000010200 ffff888012842c80 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2572, tgid 2572 (kworker/u17:0), ts 13571791526, free_ts 0 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x2db/0x350 mm/page_alloc.c:1570 prep_new_page mm/page_alloc.c:1577 [inline] get_page_from_freelist+0xfed/0x2d30 mm/page_alloc.c:3221 __alloc_pages+0x1cb/0x4a0 mm/page_alloc.c:4477 alloc_pages+0x1aa/0x270 mm/mempolicy.c:2279 alloc_slab_page mm/slub.c:1862 [inline] allocate_slab+0x25f/0x390 mm/slub.c:2009 new_slab mm/slub.c:2062 [inline] ___slab_alloc+0xbc3/0x15d0 mm/slub.c:3215 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3314 __slab_alloc_node mm/slub.c:3367 [inline] slab_alloc_node mm/slub.c:3460 [inline] __kmem_cache_alloc_node+0x143/0x350 mm/slub.c:3509 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1076 kmalloc include/linux/slab.h:579 [inline] kzalloc include/linux/slab.h:700 [inline] alloc_bprm+0x51/0xba0 fs/exec.c:1513 kernel_execve+0xaf/0x500 fs/exec.c:1988 call_usermodehelper_exec_async+0x260/0x4e0 kernel/umh.c:110 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 page_owner free stack trace missing Memory state around the buggy address: ffff888023f60f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888023f60f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888023f61000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888023f61080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888023f61100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the bug is already fixed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to change bug's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the bug is a duplicate of another bug, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
