================================================================== BUG: KASAN: slab-use-after-free in nlmsg_put_answer include/net/netlink.h:1041 [inline] BUG: KASAN: slab-use-after-free in netlink_dump_done+0x54d/0x890 net/netlink/af_netlink.c:2228 Read of size 4 at addr ffff8881bb35b9b4 by task syz.0.279/6738 CPU: 0 UID: 0 PID: 6738 Comm: syz.0.279 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 nlmsg_put_answer include/net/netlink.h:1041 [inline] netlink_dump_done+0x54d/0x890 net/netlink/af_netlink.c:2228 netlink_dump+0xacb/0xf40 net/netlink/af_netlink.c:2365 netlink_recvmsg+0x690/0xa50 net/netlink/af_netlink.c:1972 sock_recvmsg_nosec net/socket.c:1078 [inline] sock_recvmsg+0x172/0x1b0 net/socket.c:1100 sock_read_iter+0x251/0x320 net/socket.c:1170 new_sync_read fs/read_write.c:493 [inline] vfs_read+0x582/0xa70 fs/read_write.c:574 ksys_read+0x150/0x270 fs/read_write.c:717 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb5eaf9c819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb5ebe08028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007fb5eb215fa0 RCX: 00007fb5eaf9c819 RDX: 000000000000009b RSI: 00002000000003c0 RDI: 0000000000000004 RBP: 00007fb5eb032c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb5eb216038 R14: 00007fb5eb215fa0 R15: 00007ffc181c9c68 Allocated by task 6739: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4538 [inline] slab_alloc_node mm/slub.c:4866 [inline] kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4918 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 netlink_sendmsg+0x5d4/0xb40 net/netlink/af_netlink.c:1865 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2592 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6739: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2685 [inline] slab_free mm/slub.c:6165 [inline] kmem_cache_free+0x189/0x630 mm/slub.c:6295 netlink_unicast_kernel net/netlink/af_netlink.c:1315 [inline] netlink_unicast+0x817/0x9b0 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1890 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2592 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff8881bb35b980 which belongs to the cache skbuff_head_cache of size 240 The buggy address is located 52 bytes inside of freed 240-byte region [ffff8881bb35b980, ffff8881bb35ba70) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8881bb35b200 pfn:0x1bb35a head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x57ff00000000240(workingset|head|node=1|zone=2|lastcpupid=0x7ff) page_type: f5(slab) raw: 057ff00000000240 ffff888160417a00 ffff88816041db88 ffffea0005cae210 raw: ffff8881bb35b200 000000080015000f 00000000f5000000 0000000000000000 head: 057ff00000000240 ffff888160417a00 ffff88816041db88 ffffea0005cae210 head: ffff8881bb35b200 000000080015000f 00000000f5000000 0000000000000000 head: 057ff00000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5552, tgid 5552 (dhcpcd), ts 37959428622, free_ts 37819349212 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1868 prep_new_page mm/page_alloc.c:1876 [inline] get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3956 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5236 alloc_slab_page mm/slub.c:3292 [inline] allocate_slab+0x77/0x660 mm/slub.c:3481 new_slab mm/slub.c:3539 [inline] refill_objects+0x331/0x3c0 mm/slub.c:7175 refill_sheaf mm/slub.c:2812 [inline] __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615 alloc_from_pcs mm/slub.c:4717 [inline] slab_alloc_node mm/slub.c:4851 [inline] kmem_cache_alloc_node_noprof+0x441/0x690 mm/slub.c:4918 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_skb_with_frags+0xc8/0x760 net/core/skbuff.c:6763 sock_alloc_send_pskb+0x878/0x990 net/core/sock.c:2995 unix_dgram_sendmsg+0x460/0x18e0 net/unix/af_unix.c:2127 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] sock_write_iter+0x49b/0x4f0 net/socket.c:1195 do_iter_readv_writev+0x619/0x8c0 fs/read_write.c:-1 vfs_writev+0x33c/0x990 fs/read_write.c:1059 do_writev+0x154/0x2e0 fs/read_write.c:1105 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 page last free pid 5552 tgid 5552 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1412 [inline] __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2953 mm_free_pgd kernel/fork.c:585 [inline] __mmdrop+0xb5/0x750 kernel/fork.c:727 mmdrop include/linux/sched/mm.h:55 [inline] mmdrop_sched include/linux/sched/mm.h:83 [inline] mmdrop_lazy_tlb_sched include/linux/sched/mm.h:110 [inline] finish_task_switch+0x449/0x920 kernel/sched/core.c:5180 context_switch kernel/sched/core.c:5301 [inline] __schedule+0x15e5/0x52d0 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0x164/0x360 kernel/sched/core.c:7008 schedule_hrtimeout_range_clock+0x1e7/0x320 kernel/time/sleep_timeout.c:207 poll_schedule_timeout+0xd0/0x1a0 fs/select.c:241 do_poll fs/select.c:954 [inline] do_sys_poll+0x7e8/0x1120 fs/select.c:1004 __do_sys_ppoll fs/select.c:1106 [inline] __se_sys_ppoll+0x209/0x2b0 fs/select.c:1086 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff8881bb35b880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc ffff8881bb35b900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8881bb35b980: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881bb35ba00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc ffff8881bb35ba80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================