patch 9.1.1143: illegal memory access when putting a register

Problem:  illegal memory access when putting a register
Solution: make sure cursor column doesn't become negative

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

Author: chrisbra

src/register.c

@@ -2249,7 +2249,7 @@ do_put(
 	    // Put the '] mark on the first byte of the last inserted character.
 	    // Correct the length for change in indent.
 	    curbuf->b_op_end.lnum = new_lnum;
-	    col = (colnr_T)y_array[y_size - 1].length - lendiff;
+	    col = MAX(0, (colnr_T)y_array[y_size - 1].length - lendiff);
 	    if (col > 1)
 	    {
 		curbuf->b_op_end.col = col - 1;

src/testdir/test_registers.vim

@@ -1123,4 +1123,21 @@ func Test_register_redir_display()
   call setreg(1, a[0], a[1])
 endfunc
 
+" this caused an illegal memory access and a crash
+func Test_register_cursor_column_negative()
+  CheckRunVimInTerminal
+  let script =<< trim END
+    f XREGISTER
+    call setline(1, 'abcdef a')
+    call setreg("a", "\n", 'c')
+    call cursor(1, 7)
+    call feedkeys("i\<C-R>\<C-P>azyx$#\<esc>", 't')
+  END
+  call writefile(script, 'XRegister123', 'D')
+  let buf = RunVimInTerminal('-S XRegister123', {})
+  call term_sendkeys(buf, "\<c-g>")
+  call WaitForAssert({-> assert_match('XREGISTER', term_getline(buf, 19))})
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1143,
 /**/
     1142,
 /**/