Mercurial > vim
changeset 33422:25d250a74bb6 v9.0.1969
patch 9.0.1969: [security] buffer-overflow in trunc_string()
Commit: https://github.com/vim/vim/commit/3bd7fa12e146c6051490d048a4acbfba974eeb04
Author: Christian Brabandt <cb@256bit.org>
Date: Mon Oct 2 20:59:08 2023 +0200
patch 9.0.1969: [security] buffer-overflow in trunc_string()
Problem: buffer-overflow in trunc_string()
Solution: Add NULL at end of buffer
Currently trunc_string() assumes that when the string is too long,
buf[e-1] will always be writeable. But that assumption may not always be
true. The condition currently looks like this
else if (e + 3 < buflen)
[...]
else
{
// can't fit in the "...", just truncate it
buf[e - 1] = NUL;
}
but this means, we may run into the last else clause with e still being
larger than buflen. So a buffer overflow occurs.
So instead of using `buf[e - 1]`, let's just always
truncate at `buf[buflen - 1]` which should always be writable.
Signed-off-by: Christian Brabandt <cb@256bit.org>
| author | Christian Brabandt <cb@256bit.org> |
|---|---|
| date | Mon, 02 Oct 2023 21:30:04 +0200 |
| parents | ded7dd08215f |
| children | 6557be7718fb |
| files | src/message.c src/testdir/test_crash.vim src/version.c |
| diffstat | 3 files changed, 10 insertions(+), 1 deletions(-) [+] |
line wrap: on
line diff
--- a/src/message.c +++ b/src/message.c @@ -353,7 +353,7 @@ trunc_string( else { // can't fit in the "...", just truncate it - buf[e - 1] = NUL; + buf[buflen - 1] = NUL; } }
--- a/src/testdir/test_crash.vim +++ b/src/testdir/test_crash.vim @@ -66,6 +66,12 @@ func Test_crash1() \ ' && echo "crash 7: [OK]" >> X_crash1_result.txt' .. "\<cr>") call TermWait(buf, 3000) + let file = 'crash/vim_msg_trunc_poc' + let args = printf(cmn_args, vim, file) + call term_sendkeys(buf, args .. + \ ' || echo "crash 8: [OK]" >> X_crash1_result.txt' .. "\<cr>") + call TermWait(buf, 3000) + " clean up exe buf .. "bw!" @@ -79,6 +85,7 @@ func Test_crash1() \ 'crash 5: [OK]', \ 'crash 6: [OK]', \ 'crash 7: [OK]', + \ 'crash 8: [OK]', \ ] call assert_equal(expected, getline(1, '$'))