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BUG: KASAN: use-after-free in ip_check_mc_rcu+0x63a/0x6a0 net/ipv4/igmp.c:2738
Read of size 8 at addr ffff8880a9c9dd80 by task syz-executor.5/14365

CPU: 0 PID: 14365 Comm: syz-executor.5 Not tainted 4.19.184-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+0x1fc/0x2ef lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
 ip_check_mc_rcu+0x63a/0x6a0 net/ipv4/igmp.c:2738
 __mkroute_output net/ipv4/route.c:2267 [inline]
 ip_route_output_key_hash_rcu+0x24be/0x3060 net/ipv4/route.c:2547
 ip_route_output_key_hash+0x1c6/0x320 net/ipv4/route.c:2375
 __ip_route_output_key include/net/route.h:124 [inline]
 ip_route_output_flow+0x23/0x150 net/ipv4/route.c:2632
 udp_sendmsg+0x19ce/0x2550 net/ipv4/udp.c:1101
 inet_sendmsg+0x132/0x5a0 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:632
 ___sys_sendmsg+0x3b3/0x8e0 net/socket.c:2115
 __sys_sendmmsg+0x195/0x470 net/socket.c:2210
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2236
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f795c743188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 000000000800001d RSI: 0000000020007fc0 RDI: 0000000000000004
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffe3a3e17ef R14: 00007f795c743300 R15: 0000000000022000

Allocated by task 14365:
 kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
 kmalloc include/linux/slab.h:515 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 ip_mc_add1_src net/ipv4/igmp.c:1986 [inline]
 ip_mc_add_src+0x999/0xd50 net/ipv4/igmp.c:2110
 ip_mc_source+0xa49/0x1030 net/ipv4/igmp.c:2431
 do_ip_setsockopt.constprop.0+0x31d/0x3ba0 net/ipv4/ip_sockglue.c:996
 ip_setsockopt+0x44/0xf0 net/ipv4/ip_sockglue.c:1246
 tcp_setsockopt+0x86/0xd0 net/ipv4/tcp.c:3108
 __sys_setsockopt+0x14d/0x240 net/socket.c:1901
 __do_sys_setsockopt net/socket.c:1912 [inline]
 __se_sys_setsockopt net/socket.c:1909 [inline]
 __x64_sys_setsockopt+0xba/0x150 net/socket.c:1909
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 14353:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcc/0x210 mm/slab.c:3822
 ip_mc_del1_src+0x654/0x7a0 net/ipv4/igmp.c:1899
 ip_mc_del_src.isra.0+0x2d8/0x920 net/ipv4/igmp.c:1940
 ip_mc_leave_src.isra.0+0x102/0x240 net/ipv4/igmp.c:2246
 ip_mc_drop_socket+0x11a/0x260 net/ipv4/igmp.c:2700
 inet_release+0x49/0x1e0 net/ipv4/af_inet.c:414
 __sock_release+0xcd/0x2a0 net/socket.c:579
 sock_close+0x15/0x20 net/socket.c:1140
 __fput+0x2ce/0x890 fs/file_table.c:278
 task_work_run+0x148/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x251/0x2a0 arch/x86/entry/common.c:167
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
 do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a9c9dd80
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
 64-byte region [ffff8880a9c9dd80, ffff8880a9c9ddc0)
The buggy address belongs to the page:
page:ffffea0002a72740 count:1 mapcount:0 mapping:ffff88813bff0340 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea00027cf248 ffffea00027a7b08 ffff88813bff0340
raw: 0000000000000000 ffff8880a9c9d000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a9c9dc80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880a9c9dd00: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff8880a9c9dd80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff8880a9c9de00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880a9c9de80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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