From: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Date: Thu, 23 Jul 2026 15:58:37 +0000 (+0900)
Subject: patch 9.2.0846: [security]: heap buffer overflow in set_sofo()
X-Git-Tag: v9.2.0846^0
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;ds=inline;p=thirdparty%2Fvim.git

patch 9.2.0846: [security]: heap buffer overflow in set_sofo()

Problem:  [security]: heap buffer overflow in set_sofo()
          (Yazan Balawneh)
Solution: Reset sl_sal_first (Yasuhiro Matsumoto).

A crafted spell file with an empty SN_SAL section before an SN_SOFO
section reaches set_sofo() with sl_sal_first[] already set to -1 by
set_sal_first(). The counting loop then under-counts colliding
multi-byte "from" characters, allocates an undersized list and writes
past its end.

Github Security Advisory:
https://github.com/vim/vim/security/advisories/GHSA-9jqx-hgpr-6v64

Signed-off-by: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
---

diff --git a/src/spellfile.c b/src/spellfile.c
index 8000cdb550..e90c89b73d 100644
--- a/src/spellfile.c
+++ b/src/spellfile.c
@@ -1434,7 +1434,9 @@ set_sofo(slang_T *lp, char_u *from, char_u *to)
 	lp->sl_sofo = TRUE;
 
 	// First count the number of items for each list.  Temporarily use
-	// sl_sal_first[] for this.
+	// sl_sal_first[] for this.  Reset it first: a preceding SN_SAL section
+	// may have set the entries to -1 via set_sal_first().
+	vim_memset(lp->sl_sal_first, 0, sizeof(salfirst_T) * 256);
 	for (p = from, s = to; *p != NUL && *s != NUL; )
 	{
 	    c = mb_cptr2char_adv(&p);
diff --git a/src/testdir/test_spellfile.vim b/src/testdir/test_spellfile.vim
index fa3fb14fd8..b8e710eb64 100644
--- a/src/testdir/test_spellfile.vim
+++ b/src/testdir/test_spellfile.vim
@@ -319,6 +319,11 @@ func Test_spellfile_format_error()
   " SN_SOFO: multi-byte characters in sofofrom and sofoto
   call Spellfile_Test(0z0600000000080002CF810002CF82FF000000000000000000000000, '')
 
+  " SN_SAL (empty) followed by SN_SOFO with two multi-byte 'from' characters
+  " sharing the same low byte.  A preceding SN_SAL poisons sl_sal_first[], so
+  " without a reset set_sofo() under-counts and writes out of bounds.
+  call Spellfile_Test(0z05000000000300000006000000000A0004CAABCEAB00024142FF000000000000000000000000, '')
+
   " SN_COMPOUND: compmax is less than 2
   call Spellfile_Test(0z08000000000101, 'E759:')
 
diff --git a/src/version.c b/src/version.c
index a93ef03842..5547cf4d52 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    846,
 /**/
     845,
 /**/