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BUG: KASAN: slab-out-of-bounds in fl6_update_dst+0x2cb/0x2f0 net/ipv6/exthdrs.c:1356
Read of size 16 at addr ffff8880a49e39d8 by task syz-executor.2/8387

CPU: 1 PID: 8387 Comm: syz-executor.2 Not tainted 5.7.0-rc2-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+0x128/0x182 lib/dump_stack.c:118
 print_address_description.constprop.8.cold.10+0x9/0x317 mm/kasan/report.c:382
 __kasan_report.cold.11+0x35/0x4d mm/kasan/report.c:511
 kasan_report+0x32/0x50 mm/kasan/common.c:625
 fl6_update_dst+0x2cb/0x2f0 net/ipv6/exthdrs.c:1356
 sctp_v6_get_dst+0x49c/0x1590 net/sctp/ipv6.c:276
 sctp_transport_route+0x124/0x330 net/sctp/transport.c:297
 sctp_assoc_add_peer+0x511/0xea0 net/sctp/associola.c:659
 sctp_connect_new_asoc+0x139/0x490 net/sctp/socket.c:1092
 sctp_sendmsg_new_asoc net/sctp/socket.c:1694 [inline]
 sctp_sendmsg+0x118e/0x1c60 net/sctp/socket.c:2004
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xac/0xe0 net/socket.c:672
 ____sys_sendmsg+0x376/0x760 net/socket.c:2362
 ___sys_sendmsg+0xe4/0x160 net/socket.c:2416
 __sys_sendmmsg+0x145/0x330 net/socket.c:2506
 __do_sys_sendmmsg net/socket.c:2535 [inline]
 __se_sys_sendmmsg net/socket.c:2532 [inline]
 __x64_sys_sendmmsg+0x94/0x100 net/socket.c:2532
 do_syscall_64+0xc6/0x620 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c829
Code: 0d 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3eb0861c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004fc3e0 RCX: 000000000045c829
RDX: 0000000000000001 RSI: 0000000020000140 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008e0 R14: 00000000004cb843 R15: 00007f3eb08626d4

Allocated by task 8387:
 save_stack+0x19/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc.constprop.17+0xc1/0xd0 mm/kasan/common.c:495
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x164/0x7b0 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 sock_kmalloc+0x83/0xc0 net/core/sock.c:2166
 ipv6_renew_options+0x1f2/0x8b0 net/ipv6/exthdrs.c:1275
 do_ipv6_setsockopt.isra.8+0x21ec/0x36e0 net/ipv6/ipv6_sockglue.c:435
 ipv6_setsockopt+0x6e/0xe0 net/ipv6/ipv6_sockglue.c:949
 sctp_setsockopt+0x14a/0x58e0 net/sctp/socket.c:4685
 __sys_setsockopt+0x228/0x430 net/socket.c:2132
 __do_sys_setsockopt net/socket.c:2148 [inline]
 __se_sys_setsockopt net/socket.c:2145 [inline]
 __x64_sys_setsockopt+0xb5/0x150 net/socket.c:2145
 do_syscall_64+0xc6/0x620 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880a49e3980
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 88 bytes inside of
 96-byte region [ffff8880a49e3980, ffff8880a49e39e0)
The buggy address belongs to the page:
page:ffffea00029278c0 refcount:1 mapcount:0 mapping:0000000036b272c3 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00028790c8 ffffea00027aac48 ffff8880aa400540
raw: 0000000000000000 ffff8880a49e3000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a49e3880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a49e3900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a49e3980: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
                                                    ^
 ffff8880a49e3a00: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
 ffff8880a49e3a80: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
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