On Mon, Dec 13, 2021 at 01:05:43AM +0800, Coly Li wrote:

+	/*
+	 * parameters of bitmap_set/clear are unsigned int.
+	 * Given currently size of nvm is far from exceeding this limit,
+	 * so only add a WARN_ON message.
+	 */
+	WARN_ON(BITS_TO_LONGS(ns->pages_total) > UINT_MAX);
+	ns->pages_bitmap = kvcalloc(BITS_TO_LONGS(ns->pages_total),
+				    sizeof(unsigned long), GFP_KERNEL);

BITS_TO_LONGS() has a potential integer overflow if we're talking about
truly giant numbers.  It will return zero if ns->pages_total is more
than U64_MAX - 64.  In that case kvcalloc() will return ZERO_SIZE_PTR.

Btw, kvcalloc() will never let you allocate more than INT_MAX.  It will
trigger a WARN_ONCE().  If people want to allocate more than 2GB of RAM
then they have to plan ahead of time and use vmalloc().

regards,
dan carpenter