# HG changeset patch
# User Christian Brabandt <cb@256bit.org>
# Date 1702217763 -3600
# Node ID 3b8089d550eb47e688f46d78f162e75d7f6f6ecc
# Parent  242b964d626947c9e8dc16d9f8f12e9bbf3205dd
patch 9.0.2141: [security]: buffer-overflow in suggest_trie_walk

Commit: https://github.com/vim/vim/commit/0fb375aae608d7306b4baf9c1f906961f32e2abf
Author: Christian Brabandt <cb@256bit.org>
Date:   Wed Nov 29 10:23:39 2023 +0100

    patch 9.0.2141: [security]: buffer-overflow in suggest_trie_walk

    Problem:  [security]: buffer-overflow in suggest_trie_walk
    Solution: Check n before using it as index into byts array

    Basically, n as an index into the byts array, can point to beyond the byts
    array. So let's double check, that n is within the expected range after
    incrementing it from sp->ts_curi and bail out if it would be invalid.

    Reported by @henices, thanks!

    Signed-off-by: Christian Brabandt <cb@256bit.org>

diff --git a/src/spellsuggest.c b/src/spellsuggest.c
--- a/src/spellsuggest.c
+++ b/src/spellsuggest.c
@@ -2175,6 +2175,13 @@ suggest_trie_walk(
 	    // - Skip the byte if it's equal to the byte in the word,
 	    //   accepting that byte is always better.
 	    n += sp->ts_curi++;
+
+	    // break out, if we would be accessing byts buffer out of bounds
+	    if (byts == slang->sl_fbyts && n >= slang->sl_fbyts_len)
+	    {
+		got_int = TRUE;
+		break;
+	    }
 	    c = byts[n];
 	    if (soundfold && sp->ts_twordlen == 0 && c == '*')
 		// Inserting a vowel at the start of a word counts less,
diff --git a/src/testdir/crash/poc_suggest_trie_walk b/src/testdir/crash/poc_suggest_trie_walk
new file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..c79b6eeb5c340057d353903142910f4df292581a
GIT binary patch
literal 100
zc$_OvRY=WC&QHnAOSer)O)5=i;L6K4P%ua|s0!CL++e^}oSCDTmtT}CR#0MTAn}5k
Y0U=^wT4agDlK`;|Kx`Ex(JEU80AW)fkN^Mx

diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -135,6 +135,13 @@ func Test_crash1_2()
     \ '  && echo "crash 2: [OK]" >> '.. result .. "\<cr>")
   call TermWait(buf, 350)
 
+  let file = 'crash/poc_suggest_trie_walk'
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
+  let args = printf(cmn_args, vim, file)
+  call term_sendkeys(buf, args ..
+    \ '  && echo "crash 3: [OK]" >> '.. result .. "\<cr>")
+  call TermWait(buf, 150)
+
   " clean up
   exe buf .. "bw!"
 
@@ -143,6 +150,7 @@ func Test_crash1_2()
   let expected = [
       \ 'crash 1: [OK]',
       \ 'crash 2: [OK]',
+      \ 'crash 3: [OK]',
       \ ]
 
   call assert_equal(expected, getline(1, '$'))
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2141,
+/**/
     2140,
 /**/
     2139,