Crash when searching for column with number between 2^64 - 1 and 2 ^ 64 - 2 ^ 31

[rgreenblatt]

NVIM v0.4.0-dev
VIM - Vi IMproved 8.1 compiled from source today does not crash.

• Operating system/version: Ubuntu 18.10
• Terminal name/version: st
• $TERM: xterm-256color and st-256color both reproduce the problem

Steps to reproduce using nvim -u NORC

nvim -u NORC
/\v%18446744071562067968c

Will yield:

nvim: /build/neovim-5zUQcT/neovim-0.4.0+ubuntu1+git201904202022-43356a4-eada8be/src/nvim/regexp_nfa.c:5926: nfa_regmatch: Assertion `t->state->val >= 0 && reginput >= regline && (uintmax_t)(reginput - regline) <= UINTMAX_MAX - 1' failed.
                                               
[1]    30948 abort (core dumped)  /usr/bin/nvim -u NORC

Any number between 18446744071562067968 (2^64 - 2^31) and 18446744073709551615 (2^64 - 1) causes a crash for me. The issue doesn't reproduce for 2^64 - 2^32 but I am not sure where the issue stops occuring between 2^64 - 2^31 and 2^64 - 2^32.

I ran into this while generating patterns using c++ and overflowing a size_t value. I can't imagine this is a problem for anyone, but it does seem at least to me like something that should get fixed if possible.

[mhinz]

This assert is hit:

neovim/src/nvim/regexp_nfa.c

Lines 5924 to 5926 in 43356a4

	assert(t->state->val >= 0
	&& reginput >= regline
	&& (uintmax_t)(reginput - regline) <= UINTMAX_MAX - 1);

Introduced by: 2ceb1c7

[justinmk]

Should show an EMSG error instead of asserting.

I can't imagine that Vim does anything useful with such a value...

[gafeol]

Hi, I was trying to solve this issue, but I’ve been unable to create an error message on the regexp_nfa.c file.
My biggest problem is figuring out where to create the error message with EMSG, I've tried substituting the assert on line 5924 for an if:

But then when reproducing the issue I get these errors:

Should I stop the execution of the function nfa_regmatch with some return value other than just false?

[justinmk]

But then when reproducing the issue I get these errors:

That is what I would expect. What else is the editor supposed to do with such a column?

[jamessan]

v8.1.0908 is relevant.