Heap-based Buffer Overflow in vim/vim


Reported on

Jan 8th 2022


Heap-buffer-overflow in vim


./vim -u NONE -X -Z -e -s -S minpoc -c :qa!

Proof of Concept

minpoc is here. #bt

Program received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
50      ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
──────────────────────────────────────────────────────────────────────────────────────────────────[ REGISTERS ]──────────────────────────────────────────────────────────────────────────────────────────────────
 RAX  0x0
 RBX  0x7ffff771c880 ◂— 0x7ffff771c880
 RCX  0x7ffff787718b (raise+203) ◂— mov    rax, qword ptr [rsp + 0x108]
 RDX  0x0
 RDI  0x2
 RSI  0x7fffffffbee0 ◂— 0x0
 R8   0x0
 R9   0x7fffffffbee0 ◂— 0x0
 R10  0x8
 R11  0x246
 R12  0x7fffffffc150 —▸ 0x805870 ◂— 0x7f00367074 /* 'tp6' */
 R13  0x10
 R14  0x7ffff7ffb000 ◂— 0x6c6c616d00001000
 R15  0x1
 RBP  0x7fffffffc230 ◂— 0x2de
 RSP  0x7fffffffbee0 ◂— 0x0
 RIP  0x7ffff787718b (raise+203) ◂— mov    rax, qword ptr [rsp + 0x108]
───────────────────────────────────────────────────────────────────────────────────────────────────[ DISASM ]────────────────────────────────────────────────────────────────────────────────────────────────────
 ► 0x7ffff787718b <raise+203>    mov    rax, qword ptr [rsp + 0x108]
   0x7ffff7877193 <raise+211>    xor    rax, qword ptr fs:[0x28]
   0x7ffff787719c <raise+220>    jne    raise+260                <raise+260>
   0x7ffff78771c4 <raise+260>    call   __stack_chk_fail                <__stack_chk_fail>
   0x7ffff78771c9                nop    dword ptr [rax]
   0x7ffff78771d0 <killpg>       endbr64 
   0x7ffff78771d4 <killpg+4>     test   edi, edi
   0x7ffff78771d6 <killpg+6>     js     killpg+16                <killpg+16>
   0x7ffff78771d8 <killpg+8>     neg    edi
   0x7ffff78771da <killpg+10>    jmp    kill                <kill>
   0x7ffff78771df <killpg+15>    nop    
────────────────────────────────────────────────────────────────────────────────────────────────────[ STACK ]────────────────────────────────────────────────────────────────────────────────────────────────────
00:0000rsi r9 rsp 0x7fffffffbee0 ◂— 0x0
01:00080x7fffffffbee8 —▸ 0x663998 (check_termcode+72) ◂— cmp    rax, 0
02:00100x7fffffffbef0 ◂— 0x40 /* '@' */
03:00180x7fffffffbef8 ◂— 0x7000000101
04:00200x7fffffffbf00 ◂— 0x8
05:00280x7fffffffbf08 ◂— 0x1
06:00300x7fffffffbf10 ◂— 0x0
07:00380x7fffffffbf18 ◂— 0x770000007c /* '|' */
──────────────────────────────────────────────────────────────────────────────────────────────────[ BACKTRACE ]──────────────────────────────────────────────────────────────────────────────────────────────────
 ► f 0   0x7ffff787718b raise+203
   f 1   0x7ffff7856859 abort+299
   f 2   0x7ffff78c13ee __libc_message+670
   f 3   0x7ffff78c947c
   f 4   0x7ffff78cc83a _int_malloc+3146
   f 5   0x7ffff78ce2d4 malloc+116
   f 6         0x4063a7 lalloc+87
   f 7         0x40634a alloc+26
pwndbg> bt
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1  0x00007ffff7856859 in __GI_abort () at abort.c:79
#2  0x00007ffff78c13ee in __libc_message (action=action@entry=do_abort, fmt=fmt@entry=0x7ffff79eb285 "%s\n") at ../sysdeps/posix/libc_fatal.c:155
#3  0x00007ffff78c947c in malloc_printerr (str=str@entry=0x7ffff79e9556 "malloc(): corrupted top size") at malloc.c:5347
#4  0x00007ffff78cc83a in _int_malloc (av=av@entry=0x7ffff7a1cb80 <main_arena>, bytes=bytes@entry=734) at malloc.c:4107
#5  0x00007ffff78ce2d4 in __GI___libc_malloc (bytes=734) at malloc.c:3058
#6  0x00000000004063a7 in lalloc (size=734, message=1) at alloc.c:248
#7  0x000000000040634a in alloc (size=734) at alloc.c:151
#8  0x0000000000561418 in block_insert (oap=0x7fffffffc7c8, s=0x8d0dc0 "HI4KEYMRJYSDXNEN1JLUM6PA6590516 2K186A8IDsss", b_insert=0, bdp=0x7fffffffc4d0) at ops.c:551
#9  0x000000000056116e in op_insert (oap=0x7fffffffc7c8, count1=1) at ops.c:1692
#10 0x00000000005663cc in do_pending_operator (cap=0x7fffffffc758, old_col=0, gui_yank=0) at ops.c:4160
#11 0x000000000054f207 in normal_cmd (oap=0x7fffffffc7c8, toplevel=1) at normal.c:1145
#12 0x00000000004aa97a in exec_normal (was_typed=0, use_vpeekc=0, may_use_terminal_loop=0) at ex_docmd.c:8635
#13 0x00000000004aa81b in exec_normal_cmd (cmd=0x805355 "0r\te\026\067QG4QAHI4KEYMRJYSDXNEN1JLUM6PA6590516 2K186A8IDsss", remap=0, silent=0) at ex_docmd.c:8598
#14 0x00000000004aa73c in ex_normal (eap=0x7fffffffcb38) at ex_docmd.c:8516
#15 0x00000000004a1535 in do_one_cmd (cmdlinep=0x7fffffffd3d8, flags=7, cstack=0x7fffffffcd90, fgetline=0x5feed0 <getsourceline>, cookie=0x7fffffffd530) at ex_docmd.c:2570
#16 0x000000000049e6e2 in do_cmdline (cmdline=0x805220 "00", fgetline=0x5feed0 <getsourceline>, cookie=0x7fffffffd530, flags=7) at ex_docmd.c:993
#17 0x00000000005fe817 in do_source (fname=0x7fd963 "/home/zxq/CVE_testing/minpoc", check_other=0, is_vimrc=0, ret_sid=0x0) at scriptfile.c:1423
#18 0x00000000005fdbc6 in cmd_source (fname=0x7fd963 "/home/zxq/CVE_testing/minpoc", eap=0x7fffffffd798) at scriptfile.c:985
#19 0x00000000005fdadc in ex_source (eap=0x7fffffffd798) at scriptfile.c:1011
#20 0x00000000004a1535 in do_one_cmd (cmdlinep=0x7fffffffe038, flags=11, cstack=0x7fffffffd9f0, fgetline=0x0, cookie=0x0) at ex_docmd.c:2570
#21 0x000000000049e6e2 in do_cmdline (cmdline=0x7fd900 "so /home/zxq/CVE_testing/minpoc", fgetline=0x0, cookie=0x0, flags=11) at ex_docmd.c:993
#22 0x000000000049f334 in do_cmdline_cmd (cmd=0x7fd900 "so /home/zxq/CVE_testing/minpoc") at ex_docmd.c:587
#23 0x0000000000728903 in exe_commands (parmp=0x7e8a58 <params>) at main.c:3084
#24 0x000000000072795a in vim_main2 () at main.c:774
#25 0x00000000007252c1 in main (argc=11, argv=0x7fffffffe238) at main.c:426
#26 0x00007ffff78580b3 in __libc_start_main (main=0x724d60 <main>, argc=11, argv=0x7fffffffe238, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffe228) at ../csu/libc-start.c:308
#27 0x000000000040617e in _start ()

We are processing your report and will contact the vim team within 24 hours. 5 months ago
We have contacted a member of the vim team and are waiting to hear back 5 months ago
Bram Moolenaar
5 months ago


This POC is much too long. Please reduce it to the minimal needed to reproduce the issue.

We have sent a follow up to the vim team. We will try again in 7 days. 5 months ago
4 months ago


POC is here.

zfeixq modified the report
4 months ago
zfeixq modified the report
4 months ago
Bram Moolenaar validated this vulnerability 4 months ago
zfeixq has been awarded the disclosure bounty
The fix bounty is now up for grabs
Bram Moolenaar
4 months ago


Thanks for the new POC, I can reproduce the problem. I'll make a fix.

Bram Moolenaar
4 months ago


Found a simpler way to reproduce the problem. With the fix it is in patch 8.2.4120.

Bram Moolenaar confirmed that a fix has been merged on 9f8c30 4 months ago
Bram Moolenaar has been awarded the fix bounty
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