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BUG: KASAN: slab-out-of-bounds in fl6_update_dst+0x2bb/0x2c0 net/ipv6/exthdrs.c:1356
Read of size 16 at addr ffff8880186c9cd8 by task syz-executor.4/29860

CPU: 0 PID: 29860 Comm: syz-executor.4 Not tainted 5.7.0-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+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 fl6_update_dst+0x2bb/0x2c0 net/ipv6/exthdrs.c:1356
 udpv6_sendmsg+0x185a/0x2b50 net/ipv6/udp.c:1431
 inet6_sendmsg+0x99/0xe0 net/ipv6/af_inet6.c:638
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x32f/0x810 net/socket.c:2352
 ___sys_sendmsg+0x100/0x170 net/socket.c:2406
 __sys_sendmmsg+0x195/0x480 net/socket.c:2496
 __do_sys_sendmmsg net/socket.c:2525 [inline]
 __se_sys_sendmmsg net/socket.c:2522 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2522
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45ca69
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:00007fa424fc9c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004fc5c0 RCX: 000000000045ca69
RDX: 00000000000000c6 RSI: 0000000020006d00 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008dd R14: 00000000004cba5f R15: 00007fa424fca6d4

Allocated by task 29860:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc mm/kasan/common.c:494 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x161/0x7a0 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 sock_kmalloc net/core/sock.c:2255 [inline]
 sock_kmalloc+0xb5/0x100 net/core/sock.c:2246
 ipv6_renew_options+0x274/0x940 net/ipv6/exthdrs.c:1275
 do_ipv6_setsockopt.isra.0+0x2db4/0x4330 net/ipv6/ipv6_sockglue.c:471
 ipv6_setsockopt+0xfb/0x180 net/ipv6/ipv6_sockglue.c:900
 udpv6_setsockopt+0x5d/0xa0 net/ipv6/udp.c:1567
 __sys_setsockopt+0x248/0x480 net/socket.c:2127
 __do_sys_setsockopt net/socket.c:2143 [inline]
 __se_sys_setsockopt net/socket.c:2140 [inline]
 __x64_sys_setsockopt+0xba/0x150 net/socket.c:2140
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 29058:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 kvfree+0x42/0x50 mm/util.c:603
 __free_fdtable+0x51/0x70 fs/file.c:32
 put_files_struct fs/file.c:420 [inline]
 put_files_struct+0x248/0x2e0 fs/file.c:413
 exit_files+0x7e/0xa0 fs/file.c:445
 do_exit+0xb0f/0x2de0 kernel/exit.c:801
 do_group_exit+0x125/0x340 kernel/exit.c:904
 get_signal+0x47b/0x2510 kernel/signal.c:2739
 do_signal+0x81/0x2240 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff8880186c9c80
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 88 bytes inside of
 96-byte region [ffff8880186c9c80, ffff8880186c9ce0)
The buggy address belongs to the page:
page:ffffea000061b240 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880186c9500
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0000416f48 ffffea00024d8f48 ffff8880aa000540
raw: ffff8880186c9500 ffff8880186c9000 000000010000001e 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880186c9b80: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
 ffff8880186c9c00: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
>ffff8880186c9c80: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
                                                    ^
 ffff8880186c9d00: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
 ffff8880186c9d80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
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