nvme-pci: avoid hmb desc array idx out-of-bound when hmmaxd set.

hmb descriptor idx out-of-bound occurs in case of below conditions. preferred = 128MiB
chunk_size = 4MiB
hmmaxd = 1

Current code will not allow rmmod which will free hmb descriptors to be done successfully in above case.

"descs[i]" will be set in for-loop without seeing any conditions related to "max_entries" after a single "descs" was allocated by (max_entries = 1) in this case.

Added a condition into for-loop to check index of descriptors.

Fixes 044a9df1("nvme-pci: implement the HMB entry number and size limitations")

Signed-off-by Minwoo Im <minwoo.im.dev at gmail.com>

---
 drivers/nvme/host/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

drivers/nvme/host/pci.c +1 -2

index 762b840..c66e57d 100644
@@ -1787,7 +1787,7 @@ static int __nvme_alloc_host_mem(struct nvme_dev *dev, u64 preferred,
        if (!bufs)
                goto out_free_descs;
 
-       for (size = 0; size < preferred; size += len) {
+       for (size = 0; size < preferred && i < max_entries; size += len) {
                dma_addr_t dma_addr;
 
                len = min_t(u64, chunk_size, preferred - size);
--

2.7.4