fix #31758: out of bounds write in sparse broadcast (#31763)

Author: fredrikekre

stdlib/SparseArrays/src/higherorderfns.jl

@@ -387,7 +387,7 @@ function _map_zeropres!(f::Tf, C::SparseVecOrMat, As::Vararg{SparseVecOrMat,N})
             vals, ks, rows = _fusedupdate_all(rowsentinel, activerow, rows, ks, stopks, As)
             Cx = f(vals...)
             if !_iszero(Cx)
-                Ck > spaceC && (spaceC = expandstorage!(C, Ck + min(length(C), _sumnnzs(As...)) - (sum(ks) - N)))
+                Ck > spaceC && (spaceC = expandstorage!(C, min(length(C), Ck + _sumnnzs(As...) - (sum(ks) - N))))
                 storedinds(C)[Ck] = activerow
                 storedvals(C)[Ck] = Cx
                 Ck += 1

stdlib/SparseArrays/test/higherorderfns.jl

@@ -671,4 +671,14 @@ end
     @test w == bv .* op(av)
 end
 
+@testset "issue #31758: out of bounds write in _map_zeropres!" begin
+    y = sparsevec([2,7], [1., 2.], 10)
+    x1 = sparsevec(fill(1.0, 10))
+    x2 = sparsevec([2,7], [1., 2.], 10)
+    x3 = sparsevec(fill(1.0, 10))
+    f(x, y, z) = x == y == z == 0 ? 0.0 : NaN
+    y .= f.(x1, x2, x3)
+    @test all(isnan, y)
+end
+
 end # module