From: Christian Brabandt <cb@256bit.org>
Date: Thu, 1 Aug 2024 20:10:28 +0000 (+0200)
Subject: patch 9.1.0648: [security] double-free in dialog_changed()
X-Git-Tag: v9.1.0648^0
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b29f4abcd4b3382fa746edd1d0562b7b48c9de60;p=thirdparty%2Fvim.git

patch 9.1.0648: [security] double-free in dialog_changed()

Problem:  [security] double-free in dialog_changed()
          (SuyueGuo)
Solution: Only clear pointer b_sfname pointer, if it is different
          than the b_ffname pointer.  Don't try to free b_fname,
          set it to NULL instead.

fixes: #15403

Github Advisory:
https://github.com/vim/vim/security/advisories/GHSA-46pw-v7qw-xc2f

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

diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index ce30b8d397..0d76b3b27a 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -197,9 +197,11 @@ dialog_changed(
 	// restore to empty when write failed
 	if (empty_bufname)
 	{
-	    VIM_CLEAR(buf->b_fname);
+	    // prevent double free
+	    if (buf->b_sfname != buf->b_ffname)
+		VIM_CLEAR(buf->b_sfname);
+	    buf->b_fname = NULL;
 	    VIM_CLEAR(buf->b_ffname);
-	    VIM_CLEAR(buf->b_sfname);
 	    unchanged(buf, TRUE, FALSE);
 	}
     }
diff --git a/src/testdir/crash/dialog_changed_uaf b/src/testdir/crash/dialog_changed_uaf
new file mode 100644
index 0000000000..e37d18d6da
Binary files /dev/null and b/src/testdir/crash/dialog_changed_uaf differ
diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index 29061aa423..9aef245026 100644
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -196,6 +196,12 @@ func Test_crash1_3()
   call term_sendkeys(buf, args)
   call TermWait(buf, 50)
 
+  let file = 'crash/dialog_changed_uaf'
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let args = printf(cmn_args, vim, file)
+  call term_sendkeys(buf, args)
+  call TermWait(buf, 150)
+
   " clean up
   exe buf .. "bw!"
   bw!
diff --git a/src/version.c b/src/version.c
index 0e49ebd7a0..3ca6001269 100644
--- 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 */
+/**/
+    648,
 /**/
     647,
 /**/