CVE-2022-0261 (published 2022-01-18T16:15Z)

Heap-based Buffer Overflow in GitHub repository vim/vim prior to 8.2.

Severity: MEDIUM
CVSS v2 base score: 6.8 (AV:N/AC:M/Au:N/C:P/I:P/A:P)
CVSS v3 base score: 7.8, HIGH (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-787
cwe_name: Out-of-bounds Write
description: The product writes data past the end, or before the beginning, of the intended buffer.
extended_description: 
            
            
             
			 
         
         

Fix information:
repo_url: https://github.com/vim/vim
commit_details: repo_url: https://github.com/vim/vim
author: Bram Moolenaar
author_date: 2022-01-17 17:30:21+00:00
msg: patch 8.2.4120: block insert goes over the end of the line

Problem:    Block insert goes over the end of the line.
Solution:   Handle invalid byte better.  Fix inserting the wrong text.
repository: repo_url: https://github.com/vim/vim
repo_name: vim/vim
description: The official Vim repository
repo_language: Vim Script
owner: vim
file_changes: filename: ops.c
change_type: ModificationType.MODIFY
diff: @@ -536,24 +536,29 @@ block_insert(
 	    if (b_insert)
 	    {
 		off = (*mb_head_off)(oldp, oldp + offset + spaces);
+		spaces -= off;
+		count -= off;
 	    }
 	    else
 	    {
-		off = (*mb_off_next)(oldp, oldp + offset);
-		offset += off;
+		// spaces fill the gap, the character that's at the edge moves
+		// right
+		off = (*mb_head_off)(oldp, oldp + offset);
+		offset -= off;
 	    }
-	    spaces -= off;
-	    count -= off;
 	}
 	if (spaces < 0)  // can happen when the cursor was moved
 	    spaces = 0;
 
-	newp = alloc(STRLEN(oldp) + s_len + count + 1);
+	// Make sure the allocated size matches what is actually copied below.
+	newp = alloc(STRLEN(oldp) + spaces + s_len
+		    + (spaces > 0 && !bdp->is_short ? ts_val - spaces : 0)
+								  + count + 1);
 	if (newp == NULL)
 	    continue;
 
 	// copy up to shifted part
-	mch_memmove(newp, oldp, (size_t)(offset));
+	mch_memmove(newp, oldp, (size_t)offset);
 	oldp += offset;
 
 	// insert pre-padding
@@ -564,14 +569,21 @@ block_insert(
 	mch_memmove(newp + startcol, s, (size_t)s_len);
 	offset += s_len;
 
-	if (spaces && !bdp->is_short)
+	if (spaces > 0 && !bdp->is_short)
 	{
-	    // insert post-padding
-	    vim_memset(newp + offset + spaces, ' ', (size_t)(ts_val - spaces));
-	    // We're splitting a TAB, don't copy it.
-	    oldp++;
-	    // We allowed for that TAB, remember this now
-	    count++;
+	    if (*oldp == TAB)
+	    {
+		// insert post-padding
+		vim_memset(newp + offset + spaces, ' ',
+						    (size_t)(ts_val - spaces));
+		// we're splitting a TAB, don't copy it
+		oldp++;
+		// We allowed for that TAB, remember this now
+		count++;
+	    }
+	    else
+		// Not a TAB, no extra spaces
+		count = spaces;
 	}
 
 	if (spaces > 0)
@@ -1598,7 +1610,7 @@ op_insert(oparg_T *oap, long count1)
 		    oap->start_vcol = t;
 		}
 		else if (oap->op_type == OP_APPEND
-			&& oap->end.col + oap->end.coladd
+			&& oap->start.col + oap->start.coladd
 				>= curbuf->b_op_start_orig.col
 					      + curbuf->b_op_start_orig.coladd)
 		{

programming_language: C
filename: test_visual.vim
change_type: ModificationType.MODIFY
diff: @@ -1278,6 +1278,15 @@ func Test_visual_block_ctrl_w_f()
   au! BufNew
 endfunc
 
+func Test_visual_block_append_invalid_char()
+  " this was going over the end of the line
+  new
+  call setline(1, ['	   let xxx', 'xxxxx', 'xxxxxxxxxxx'])
+  exe "normal 0\<C-V>jjA-\<Esc>"
+  call assert_equal(['	-   let xxx', 'xxxxx   -', 'xxxxxxxx-xxx'], getline(1, 3))
+  bwipe!
+endfunc
+
 func Test_visual_reselect_with_count()
   " this was causing an illegal memory access
   let lines =<< trim END

programming_language: Lua
filename: version.c
change_type: ModificationType.MODIFY
diff: @@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4120,
 /**/
     4119,
 /**/

programming_language: Ruby