Merge branch 'master' into wip/ext-solverwip/ext-solver

1 files changed, 9 insertions, 1 deletions

diff --git a/rts/sm/Storage.c b/rts/sm/Storage.c
index 86bd1c2bb3..379d9da769 100644
--- a/rts/sm/Storage.c
+++ b/rts/sm/Storage.c
@@ -686,7 +686,15 @@ StgPtr allocate (Capability *cap, W_ n)
     CCS_ALLOC(cap->r.rCCCS,n);
     
     if (n >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
-        W_ req_blocks =  (W_)BLOCK_ROUND_UP(n*sizeof(W_)) / BLOCK_SIZE;
+        // The largest number of words such that
+        // the computation of req_blocks will not overflow.
+        W_ max_words = (HS_WORD_MAX & ~(BLOCK_SIZE-1)) / sizeof(W_);
+        W_ req_blocks;
+
+        if (n > max_words)
+            req_blocks = HS_WORD_MAX; // signal overflow below
+        else
+            req_blocks = (W_)BLOCK_ROUND_UP(n*sizeof(W_)) / BLOCK_SIZE;
 
         // Attempting to allocate an object larger than maxHeapSize
         // should definitely be disallowed.  (bug #1791)