tipc: Failed do clone local mcast rcv buffer
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BUG: KASAN: use-after-free in __skb_unlink include/linux/skbuff.h:2063 [inline]
BUG: KASAN: use-after-free in __skb_dequeue include/linux/skbuff.h:2082 [inline]
BUG: KASAN: use-after-free in __skb_queue_purge include/linux/skbuff.h:2793 [inline]
BUG: KASAN: use-after-free in tipc_mcast_xmit+0xfaa/0x1170 net/tipc/bcast.c:422
Read of size 8 at addr ffff8880a95fb500 by task syz-executor.4/27626

CPU: 0 PID: 27626 Comm: syz-executor.4 Not tainted 5.9.0-rc8-syzkaller #0
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+0x198/0x1fd lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 __skb_unlink include/linux/skbuff.h:2063 [inline]
 __skb_dequeue include/linux/skbuff.h:2082 [inline]
 __skb_queue_purge include/linux/skbuff.h:2793 [inline]
 tipc_mcast_xmit+0xfaa/0x1170 net/tipc/bcast.c:422
 tipc_sendmcast+0xaaf/0xef0 net/tipc/socket.c:865
 __tipc_sendmsg+0xee3/0x18a0 net/tipc/socket.c:1454
 tipc_sendmsg+0x4c/0x70 net/tipc/socket.c:1387
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2407
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45de59
Code: 0d b4 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 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f5bd53ecc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000002e740 RCX: 000000000045de59
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000003
RBP: 00007f5bd53ecca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000008
R13: 00007fff95b14fbf R14: 00007f5bd53ed9c0 R15: 000000000118bf2c

Allocated by task 27626:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 slab_post_alloc_hook mm/slab.h:518 [inline]
 slab_alloc_node mm/slab.c:3258 [inline]
 kmem_cache_alloc_node+0x136/0x430 mm/slab.c:3578
 __alloc_skb+0x71/0x550 net/core/skbuff.c:198
 alloc_skb_fclone include/linux/skbuff.h:1144 [inline]
 tipc_buf_acquire+0x28/0xf0 net/tipc/msg.c:76
 tipc_msg_build+0x6b8/0x10c0 net/tipc/msg.c:428
 tipc_sendmcast+0x855/0xef0 net/tipc/socket.c:859
 __tipc_sendmsg+0xee3/0x18a0 net/tipc/socket.c:1454
 tipc_sendmsg+0x4c/0x70 net/tipc/socket.c:1387
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2407
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 27626:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
 __cache_free mm/slab.c:3422 [inline]
 kmem_cache_free.part.0+0x74/0x1e0 mm/slab.c:3697
 kfree_skbmem+0x166/0x1b0 net/core/skbuff.c:643
 kfree_skb+0x7d/0x100 include/linux/refcount.h:270
 tipc_buf_append+0x6dc/0xcf0 net/tipc/msg.c:198
 tipc_msg_reassemble+0x175/0x4f0 net/tipc/msg.c:790
 tipc_mcast_xmit+0x699/0x1170 net/tipc/bcast.c:386
 tipc_sendmcast+0xaaf/0xef0 net/tipc/socket.c:865
 __tipc_sendmsg+0xee3/0x18a0 net/tipc/socket.c:1454
 tipc_sendmsg+0x4c/0x70 net/tipc/socket.c:1387
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2407
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880a95fb500
 which belongs to the cache skbuff_fclone_cache of size 456
The buggy address is located 0 bytes inside of
 456-byte region [ffff8880a95fb500, ffff8880a95fb6c8)
The buggy address belongs to the page:
page:0000000014626c10 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xa95fb
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029eeb08 ffffea00025930c8 ffff88821b777700
raw: 0000000000000000 ffff8880a95fb000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a95fb400: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc
 ffff8880a95fb480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a95fb500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8880a95fb580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a95fb600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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