syzbot

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BUG: KASAN: use-after-free in atomic_set include/asm-generic/atomic-instrumented.h:44 [inline]
BUG: KASAN: use-after-free in refcount_set include/linux/refcount.h:32 [inline]
BUG: KASAN: use-after-free in copy_net_ns+0x1e8/0x431 net/core/net_namespace.c:466
Write of size 4 at addr ffff88808ff9c080 by task syz-executor.5/9778

CPU: 0 PID: 9778 Comm: syz-executor.5 Not tainted 5.2.0-rc6-next-20190627 #24
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351
 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482
 kasan_report+0x12/0x17 mm/kasan/common.c:614
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 kasan_check_write+0x14/0x20 mm/kasan/common.c:100
 atomic_set include/asm-generic/atomic-instrumented.h:44 [inline]
 refcount_set include/linux/refcount.h:32 [inline]
 copy_net_ns+0x1e8/0x431 net/core/net_namespace.c:466
 create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:103
 unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:202
 ksys_unshare+0x444/0x980 kernel/fork.c:2828
 __do_sys_unshare kernel/fork.c:2896 [inline]
 __se_sys_unshare kernel/fork.c:2894 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:2894
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459519
Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f37f80b7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f37f80b7c90 RCX: 0000000000459519
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f37f80b86d4
R13: 00000000004c8a2c R14: 00000000004df7d0 R15: 0000000000000007

Allocated by task 9778:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
 slab_post_alloc_hook mm/slab.h:520 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc+0x121/0x710 mm/slab.c:3484
 kmem_cache_zalloc include/linux/slab.h:737 [inline]
 net_alloc net/core/net_namespace.c:410 [inline]
 copy_net_ns+0xf1/0x431 net/core/net_namespace.c:461
 create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:103
 unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:202
 ksys_unshare+0x444/0x980 kernel/fork.c:2828
 __do_sys_unshare kernel/fork.c:2896 [inline]
 __se_sys_unshare kernel/fork.c:2894 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:2894
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9778:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3426 [inline]
 kmem_cache_free+0x86/0x320 mm/slab.c:3694
 net_alloc net/core/net_namespace.c:427 [inline]
 copy_net_ns+0x3b1/0x431 net/core/net_namespace.c:461
 create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:103
 unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:202
 ksys_unshare+0x444/0x980 kernel/fork.c:2828
 __do_sys_unshare kernel/fork.c:2896 [inline]
 __se_sys_unshare kernel/fork.c:2894 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:2894
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88808ff9c080
 which belongs to the cache net_namespace(87:syz5) of size 6784
The buggy address is located 0 bytes inside of
 6784-byte region [ffff88808ff9c080, ffff88808ff9db00)
The buggy address belongs to the page:
page:ffffea00023fe700 refcount:1 mapcount:0 mapping:ffff8880932351c0 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0002511288 ffff888093d24548 ffff8880932351c0
raw: 0000000000000000 ffff88808ff9c080 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808ff9bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808ff9c000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88808ff9c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88808ff9c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808ff9c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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