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
index e1c303a0ab8793b6e6da26cedbcc8a3dc494d680..ecc0a7403d6ab968923ed217969db908352476b0 100644 (file)
--- 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 (file)
index 0000000..c79b6ee
Binary files /dev/null and b/src/testdir/crash/poc_suggest_trie_walk differ

diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index 11c5f4e014dcd17807131a25175605fb3200b28e..eef1731454d9ceb8707e72d50d29672d9968cc74 100644 (file)
--- 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
index e32e5c006dbfd817551822eb9d801174210d3805..ecb5c22304941a937d2e24e9abfd90417ee0defc 100644 (file)
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2141,
 /**/
     2140,
 /**/