patch 8.0.0879: crash when shifting with huge numberv8.0.0879

Problem:    Crash when shifting with huge number.
Solution:   Check for overflow. (Dominique Pelle, closes #1945)

1 files changed, 4 insertions, 1 deletions

diff --git a/src/ops.c b/src/ops.c
index 0f42dea00..5c58e523f 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -396,7 +396,10 @@ shift_block(oparg_T *oap, int amount)
 	return;
 
     /* total is number of screen columns to be inserted/removed */
-    total = amount * p_sw;
+    total = (int)((unsigned)amount * (unsigned)p_sw);
+    if ((total / p_sw) != amount)
+	return; /* multiplication overflow */
+
     oldp = ml_get_curline();
 
     if (!left)