Subject: KASAN: global-out-of-bounds Read in __xfrm6_tunnel_spi_lookup

From: syzbot <[email-masked]>
Date: Mon, 13 Jul 2020 23:27:20 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    be978f8f Add linux-next specific files for 20200713
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11e79167100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3fe4fccb94cbc1a6
dashboard link: https://syzkaller.appspot.com/bug?extid=cd59712012813594d659
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1430914f100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1203e95d100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]

IPVS: ftp: loaded support on port[0] = 21
==================================================================
BUG: KASAN: global-out-of-bounds in ipv6_addr_equal include/net/ipv6.h:579 [inline]
BUG: KASAN: global-out-of-bounds in xfrm6_addr_equal include/net/xfrm.h:1699 [inline]
BUG: KASAN: global-out-of-bounds in __xfrm6_tunnel_spi_lookup+0x367/0x3b0 net/ipv6/xfrm6_tunnel.c:82
Read of size 8 at addr ffffffff884ba1e0 by task syz-executor372/6812
CPU: 0 PID: 6812 Comm: syz-executor372 Not tainted 5.8.0-rc4-next-20200713-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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0x5/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 ipv6_addr_equal include/net/ipv6.h:579 [inline]
 xfrm6_addr_equal include/net/xfrm.h:1699 [inline]
 __xfrm6_tunnel_spi_lookup+0x367/0x3b0 net/ipv6/xfrm6_tunnel.c:82
 xfrm6_tunnel_spi_lookup+0x8a/0x1d0 net/ipv6/xfrm6_tunnel.c:95
 xfrmi6_rcv_tunnel+0xb9/0x100 net/xfrm/xfrm_interface.c:810
 tunnel6_rcv+0xef/0x2b0 net/ipv6/tunnel6.c:148
 ip6_protocol_deliver_rcu+0x2e8/0x1670 net/ipv6/ip6_input.c:433
 ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
 ip6_mc_input+0x411/0xea0 net/ipv6/ip6_input.c:577
 dst_input include/net/dst.h:449 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5287
 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5401
 netif_receive_skb_internal net/core/dev.c:5503 [inline]
 netif_receive_skb+0x159/0x990 net/core/dev.c:5562
 tun_rx_batched.isra.0+0x460/0x720 drivers/net/tun.c:1518
 tun_get_user+0x23b2/0x35b0 drivers/net/tun.c:1972
 tun_chr_write_iter+0xba/0x151 drivers/net/tun.c:2001
 call_write_iter include/linux/fs.h:1879 [inline]
 new_sync_write+0x422/0x650 fs/read_write.c:515
 vfs_write+0x59d/0x6b0 fs/read_write.c:595
 ksys_write+0x12d/0x250 fs/read_write.c:648
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4013a0
Code: Bad RIP value.
RSP: 002b:00007ffdf3de1d98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004013a0
RDX: 000000000000005e RSI: 0000000020000ac0 RDI: 00000000000000f0
RBP: 00007ffdf3de1db0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
The buggy address belongs to the variable:
 psi_io_proc_ops+0xa0/0x4fe0
Memory state around the buggy address:
 ffffffff884ba080: 00 00 00 00 f9 f9 f9 f9 00 00 00 00 00 00 00 00
 ffffffff884ba100: 00 00 00 00 f9 f9 f9 f9 00 00 00 00 00 00 00 00
>ffffffff884ba180: 00 00 00 00 f9 f9 f9 f9 00 00 01 f9 f9 f9 f9 f9
                                                       ^
 ffffffff884ba200: 00 00 00 07 f9 f9 f9 f9 00 00 00 f9 f9 f9 f9 f9
 ffffffff884ba280: 00 00 07 f9 f9 f9 f9 f9 00 00 00 02 f9 f9 f9 f9
==================================================================

---
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