Re: WARNING in __vunmap

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    b3a9964c Merge tag 'char-misc-5.3-rc8' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16c9f70a600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=144488c6c6c6d2b6
dashboard link: https://syzkaller.appspot.com/bug?extid=5ec9bb042ddfe9644773
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
80fee25776c2fb61e74c1ecb1a523375c2500b69)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11a30371600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+5ec9bb042ddfe9644773@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
Trying to vfree() nonexistent vm area (00000000dddfa71b)
WARNING: CPU: 0 PID: 10463 at mm/vmalloc.c:2235 __vunmap+0x148/0xa20  
mm/vmalloc.c:2234
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 10463 Comm: syz-executor.0 Not tainted 5.3.0-rc7+ #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+0x1d8/0x2f8 lib/dump_stack.c:113
 panic+0x25c/0x799 kernel/panic.c:219
 __warn+0x22f/0x230 kernel/panic.c:576
 report_bug+0x190/0x290 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 do_error_trap+0xd7/0x440 arch/x86/kernel/traps.c:272
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:291
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:__vunmap+0x148/0xa20 mm/vmalloc.c:2234
Code: 0c e8 8c 36 d0 ff eb 24 e8 85 36 d0 ff 48 c7 c7 a8 f5 8f 88 e8 69 9b  
d8 05 48 c7 c7 e5 5c 3e 88 4c 89 f6 31 c0 e8 68 18 a3 ff <0f> 0b 48 83 c4  
60 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 c7 c7 a8 f5
RSP: 0018:ffff8880a81d75b8 EFLAGS: 00010246
RAX: 4324ba28a2c9f400 RBX: 0000000000000000 RCX: ffff8880a48ce080
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffff8880a81d7640 R08: ffffffff815cfa54 R09: ffffed1015d46088
R10: ffffed1015d46088 R11: 0000000000000000 R12: ffff88808a93f708
R13: dffffc0000000000 R14: ffffc900080f7000 R15: ffffc90008108000
 __vfree mm/vmalloc.c:2299 [inline]
 vfree+0x85/0x130 mm/vmalloc.c:2329
 ipcomp_free_scratches net/xfrm/xfrm_ipcomp.c:212 [inline]
 ipcomp_free_data+0x12a/0x1d0 net/xfrm/xfrm_ipcomp.c:321
 ipcomp_init_state+0x7bf/0x8b0 net/xfrm/xfrm_ipcomp.c:373
 ipcomp6_init_state+0xb7/0x630 net/ipv6/ipcomp6.c:153
 __xfrm_init_state+0x7d0/0xbf0 net/xfrm/xfrm_state.c:2493
 xfrm_state_construct net/xfrm/xfrm_user.c:626 [inline]
 xfrm_add_sa+0x223f/0x38e0 net/xfrm/xfrm_user.c:683
 xfrm_user_rcv_msg+0x3e6/0x650 net/xfrm/xfrm_user.c:2676
 netlink_rcv_skb+0x19e/0x3d0 net/netlink/af_netlink.c:2477
 xfrm_netlink_rcv+0x74/0x90 net/xfrm/xfrm_user.c:2684
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x787/0x900 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x993/0xc50 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg net/socket.c:657 [inline]
 ___sys_sendmsg+0x60d/0x910 net/socket.c:2311
 __sys_sendmsg net/socket.c:2356 [inline]
 __do_sys_sendmsg net/socket.c:2365 [inline]
 __se_sys_sendmsg net/socket.c:2363 [inline]
 __x64_sys_sendmsg+0x17c/0x200 net/socket.c:2363
 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4598e9
Code: fd 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4880699c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004598e9
RDX: 0000000000000000 RSI: 0000000020000840 RDI: 0000000000000003
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f488069a6d4
R13: 00000000004c7812 R14: 00000000004dd0b0 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..