Add stern warning for fromListN

vector/src/Data/Vector/Generic.hs

@@ -2205,7 +2205,11 @@ fromList :: Vector v a => [a] -> v a
 {-# INLINE fromList #-}
 fromList = unstream . Bundle.fromList
 
--- | /O(n)/ Convert the first @n@ elements of a list to a vector
+-- | /O(n)/ Convert the first @n@ elements of a list to a vector. It's
+-- expected that supplied list will be exactly @n@ elements long. As
+-- optimization this function allocates buffer for @n@ elements and
+-- could be used to DoS by exhausting memory if attacker controls that
+-- parameter.
 --
 -- @
 -- fromListN n xs = 'fromList' ('take' n xs)

vector/src/Data/Vector/Primitive.hs

@@ -1690,7 +1690,11 @@ fromList :: Prim a => [a] -> Vector a
 {-# INLINE fromList #-}
 fromList = G.fromList
 
--- | /O(n)/ Convert the first @n@ elements of a list to a vector
+-- | /O(n)/ Convert the first @n@ elements of a list to a vector. It's
+-- expected that supplied list will be exactly @n@ elements long. As
+-- optimization this function allocates buffer for @n@ elements and
+-- could be used to DoS by exhausting memory if attacker controls that
+-- parameter.
 --
 -- @
 -- fromListN n xs = 'fromList' ('take' n xs)

vector/src/Data/Vector/Storable.hs

@@ -1736,7 +1736,11 @@ fromList :: Storable a => [a] -> Vector a
 {-# INLINE fromList #-}
 fromList = G.fromList
 
--- | /O(n)/ Convert the first @n@ elements of a list to a vector
+-- | /O(n)/ Convert the first @n@ elements of a list to a vector. It's
+-- expected that supplied list will be exactly @n@ elements long. As
+-- optimization this function allocates buffer for @n@ elements and
+-- could be used to DoS by exhausting memory if attacker controls that
+-- parameter.
 --
 -- @
 -- fromListN n xs = 'fromList' ('take' n xs)

vector/src/Data/Vector/Unboxed.hs

@@ -1786,7 +1786,11 @@ fromList :: Unbox a => [a] -> Vector a
 {-# INLINE fromList #-}
 fromList = G.fromList
 
--- | /O(n)/ Convert the first @n@ elements of a list to a vector
+-- | /O(n)/ Convert the first @n@ elements of a list to a vector. It's
+-- expected that supplied list will be exactly @n@ elements long. As
+-- optimization this function allocates buffer for @n@ elements and
+-- could be used to DoS by exhausting memory if attacker controls that
+-- parameter.
 --
 -- @
 -- fromListN n xs = 'fromList' ('take' n xs)