Hello,

syzbot found the following issue on:

HEAD commit: 8ab774587903 Merge tag 'trace-v5.16-5' of git://git.kernel.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1174ace6b00000 kernel config: https://syzkaller.appspot.com/x/.config?x=6d3b8fd1977c1e73 dashboard link: https://syzkaller.appspot.com/bug?extid=c8ae65286134dd1b800d 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.

IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c8ae65286134dd1b800d@syzkaller.appspotmail.com

================================================================== BUG: KASAN: use-after-free in drm_gem_object_release_handle+0xf2/0x110 drivers/gpu/drm/drm_gem.c:252 Read of size 8 at addr ffff888028419a28 by task syz-executor.2/10905

CPU: 0 PID: 10905 Comm: syz-executor.2 Not tainted 5.16.0-rc1-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x8d/0x320 mm/kasan/report.c:247 __kasan_report mm/kasan/report.c:433 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:450 drm_gem_object_release_handle+0xf2/0x110 drivers/gpu/drm/drm_gem.c:252 idr_for_each+0x113/0x220 lib/idr.c:208 drm_gem_release+0x22/0x30 drivers/gpu/drm/drm_gem.c:930 drm_file_free.part.0+0x805/0xb80 drivers/gpu/drm/drm_file.c:281 drm_file_free drivers/gpu/drm/drm_file.c:248 [inline] drm_close_helper.isra.0+0x17d/0x1f0 drivers/gpu/drm/drm_file.c:308 drm_release+0x1e6/0x530 drivers/gpu/drm/drm_file.c:495 __fput+0x286/0x9f0 fs/file_table.c:280 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:175 [inline] exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c RIP: 0023:0xf6f4e549 Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000ff954ef0 EFLAGS: 00000282 ORIG_RAX: 0000000000000006 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 00000000f7084000 RDI: 00000000f70aafac RBP: 00000000f7084000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK>

Allocated by task 10906: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] ____kasan_kmalloc mm/kasan/common.c:472 [inline] __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:522 kmalloc include/linux/slab.h:590 [inline] kzalloc include/linux/slab.h:724 [inline] __drm_gem_shmem_create+0x3d8/0x470 drivers/gpu/drm/drm_gem_shmem_helper.c:56 drm_gem_shmem_create drivers/gpu/drm/drm_gem_shmem_helper.c:116 [inline] drm_gem_shmem_create_with_handle+0x26/0x100 drivers/gpu/drm/drm_gem_shmem_helper.c:422 drm_gem_shmem_dumb_create+0x13f/0x290 drivers/gpu/drm/drm_gem_shmem_helper.c:538 drm_mode_create_dumb+0x26c/0x2f0 drivers/gpu/drm/drm_dumb_buffers.c:96 drm_ioctl_kernel+0x27d/0x4e0 drivers/gpu/drm/drm_ioctl.c:782 drm_ioctl+0x51e/0x9d0 drivers/gpu/drm/drm_ioctl.c:885 drm_compat_ioctl+0x270/0x330 drivers/gpu/drm/drm_ioc32.c:987 __do_compat_sys_ioctl+0x1c7/0x290 fs/ioctl.c:972 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+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Freed by task 10906: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0xff/0x130 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:1723 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1749 slab_free mm/slub.c:3513 [inline] kfree+0xf6/0x560 mm/slub.c:4561 drm_gem_object_free+0x58/0x80 drivers/gpu/drm/drm_gem.c:972 kref_put include/linux/kref.h:65 [inline] __drm_gem_object_put include/drm/drm_gem.h:371 [inline] drm_gem_object_put include/drm/drm_gem.h:384 [inline] drm_gem_mmap+0x4aa/0x680 drivers/gpu/drm/drm_gem.c:1132 call_mmap include/linux/fs.h:2167 [inline] mmap_region+0xd8c/0x1650 mm/mmap.c:1786 do_mmap+0x869/0xfb0 mm/mmap.c:1575 vm_mmap_pgoff+0x1b7/0x290 mm/util.c:519 ksys_mmap_pgoff+0x40d/0x5a0 mm/mmap.c:1623 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+0x2f/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Last potentially related work creation: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 __kasan_record_aux_stack+0xf5/0x120 mm/kasan/generic.c:348 kvfree_call_rcu+0x74/0x990 kernel/rcu/tree.c:3550 drop_sysctl_table+0x3c0/0x4e0 fs/proc/proc_sysctl.c:1647 unregister_sysctl_table fs/proc/proc_sysctl.c:1685 [inline] unregister_sysctl_table+0xc0/0x190 fs/proc/proc_sysctl.c:1660 neigh_sysctl_unregister+0x5b/0x80 net/core/neighbour.c:3810 addrconf_ifdown.isra.0+0xfc2/0x1630 net/ipv6/addrconf.c:3870 addrconf_notify+0xeb/0x1bb0 net/ipv6/addrconf.c:3651 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2002 call_netdevice_notifiers_extack net/core/dev.c:2014 [inline] call_netdevice_notifiers net/core/dev.c:2028 [inline] unregister_netdevice_many+0x94f/0x1790 net/core/dev.c:11077 ip6_tnl_exit_batch_net+0x5f5/0x890 net/ipv6/ip6_tunnel.c:2311 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:171 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:593 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298 worker_thread+0x658/0x11f0 kernel/workqueue.c:2445 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Second to last potentially related work creation: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 __kasan_record_aux_stack+0xf5/0x120 mm/kasan/generic.c:348 __call_rcu kernel/rcu/tree.c:2985 [inline] call_rcu+0xb1/0x740 kernel/rcu/tree.c:3065 pwq_unbound_release_workfn+0x248/0x340 kernel/workqueue.c:3738 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298 worker_thread+0x658/0x11f0 kernel/workqueue.c:2445 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff888028419800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 552 bytes inside of 1024-byte region [ffff888028419800, ffff888028419c00) The buggy address belongs to the page: page:ffffea0000a10600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28418 head:ffffea0000a10600 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888010c42dc0 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3675, ts 98683278438, free_ts 98683124629 prep_new_page mm/page_alloc.c:2418 [inline] get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4149 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5369 alloc_pages+0x1a7/0x300 mm/mempolicy.c:2191 alloc_slab_page mm/slub.c:1793 [inline] allocate_slab mm/slub.c:1930 [inline] new_slab+0x32d/0x4a0 mm/slub.c:1993 ___slab_alloc+0x918/0xfe0 mm/slub.c:3022 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3109 slab_alloc_node mm/slub.c:3200 [inline] __kmalloc_node_track_caller+0x2cb/0x360 mm/slub.c:4956 kmalloc_reserve net/core/skbuff.c:354 [inline] __alloc_skb+0xde/0x340 net/core/skbuff.c:426 alloc_skb_fclone include/linux/skbuff.h:1176 [inline] tcp_stream_alloc_skb+0x66/0x910 net/ipv4/tcp.c:861 tcp_sendmsg_locked+0xaba/0x3040 net/ipv4/tcp.c:1281 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1440 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:819 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:724 sock_write_iter+0x289/0x3c0 net/socket.c:1057 call_write_iter include/linux/fs.h:2162 [inline] new_sync_write+0x429/0x660 fs/read_write.c:503 vfs_write+0x7cd/0xae0 fs/read_write.c:590 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1338 [inline] free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1389 free_unref_page_prepare mm/page_alloc.c:3309 [inline] free_unref_page+0x19/0x690 mm/page_alloc.c:3388 skb_free_frag include/linux/skbuff.h:2949 [inline] skb_free_head net/core/skbuff.c:653 [inline] skb_release_data+0x61f/0x790 net/core/skbuff.c:677 skb_release_all net/core/skbuff.c:742 [inline] __kfree_skb+0x46/0x60 net/core/skbuff.c:756 sk_eat_skb include/net/sock.h:2652 [inline] tcp_recvmsg_locked+0x12e8/0x20d0 net/ipv4/tcp.c:2485 tcp_recvmsg+0x12b/0x550 net/ipv4/tcp.c:2531 inet_recvmsg+0x11b/0x5e0 net/ipv4/af_inet.c:850 sock_recvmsg_nosec net/socket.c:944 [inline] sock_recvmsg net/socket.c:962 [inline] sock_recvmsg net/socket.c:958 [inline] sock_read_iter+0x33c/0x470 net/socket.c:1035 call_read_iter include/linux/fs.h:2156 [inline] new_sync_read+0x5ba/0x6e0 fs/read_write.c:400 vfs_read+0x35c/0x600 fs/read_write.c:481 ksys_read+0x1ee/0x250 fs/read_write.c:619 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address: ffff888028419900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888028419980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

ffff888028419a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^ ffff888028419a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888028419b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ---------------- Code disassembly (best guess): 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d a: 10 06 adc %al,(%rsi) c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 10: 10 07 adc %al,(%rdi) 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi 16: 10 08 adc %cl,(%rax) 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1c: 00 00 add %al,(%rax) 1e: 00 00 add %al,(%rax) 20: 00 51 52 add %dl,0x52(%rcx) 23: 55 push %rbp 24: 89 e5 mov %esp,%ebp 26: 0f 34 sysenter 28: cd 80 int $0x80 * 2a: 5d pop %rbp <-- trapping instruction 2b: 5a pop %rdx 2c: 59 pop %rcx 2d: c3 retq 2e: 90 nop 2f: 90 nop 30: 90 nop 31: 90 nop 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi

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