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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 ffff88809707f178 by task syz-executor.4/18633

CPU: 1 PID: 18633 Comm: syz-executor.4 Not tainted 5.7.0-rc6-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:382
 __kasan_report.cold+0x20/0x38 mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 fl6_update_dst+0x2bb/0x2c0 net/ipv6/exthdrs.c:1356
 udpv6_sendmsg+0x1866/0x2b50 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:00007f01b6585c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004fc5c0 RCX: 000000000045ca69
RDX: 04000000000000d7 RSI: 00000000200002c0 RDI: 0000000000000004
RBP: 000000000078c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008dd R14: 00000000004cba5f R15: 00007f01b65866d4

Allocated by task 18643:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc mm/kasan/common.c:495 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
 __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:2253 [inline]
 sock_kmalloc+0xb5/0x100 net/core/sock.c:2244
 ipv6_renew_options+0x274/0x940 net/ipv6/exthdrs.c:1275
 do_ipv6_setsockopt.isra.0+0x2dcf/0x4350 net/ipv6/ipv6_sockglue.c:470
 ipv6_setsockopt+0xfb/0x180 net/ipv6/ipv6_sockglue.c:899
 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 4119:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 kernfs_fop_release+0xe7/0x190 fs/kernfs/file.c:779
 __fput+0x33e/0x880 fs/file_table.c:280
 task_work_run+0xf4/0x1b0 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165
 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 ffff88809707f100
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 120 bytes inside of
 128-byte region [ffff88809707f100, ffff88809707f180)
The buggy address belongs to the page:
page:ffffea00025c1fc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002791a48 ffffea00029eafc8 ffff8880aa000700
raw: 0000000000000000 ffff88809707f000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809707f000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88809707f080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809707f100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
                                                                ^
 ffff88809707f180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809707f200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
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