[PATCH v4 5/9] nvram: add nrf51_soc flash read method

[P J P]

From: Prasad J Pandit <pjp@fedoraproject.org>

Add nrf51_soc mmio read method to avoid NULL pointer dereference
issue.

Reported-by: Lei Sun <slei.casper@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/nvram/nrf51_nvm.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

Update v4: add explanatory comment and Reviewed-by tag
  -> https://lists.nongnu.org/archive/html/qemu-devel/2020-07/msg05309.html

diff --git a/hw/nvram/nrf51_nvm.c b/hw/nvram/nrf51_nvm.c
index f2283c1a8d..7b3460d52d 100644
--- a/hw/nvram/nrf51_nvm.c
+++ b/hw/nvram/nrf51_nvm.c
@@ -273,6 +273,15 @@ static const MemoryRegionOps io_ops = {
         .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
+static uint64_t flash_read(void *opaque, hwaddr offset, unsigned size)
+{
+    /*
+     * This is a rom_device MemoryRegion which is always in
+     * romd_mode (we never put it in MMIO mode), so reads always
+     * go directly to RAM and never come here.
+     */
+    g_assert_not_reached();
+}
 
 static void flash_write(void *opaque, hwaddr offset, uint64_t value,
         unsigned int size)
@@ -300,6 +309,7 @@ static void flash_write(void *opaque, hwaddr offset, 
uint64_t value,
 
 
 static const MemoryRegionOps flash_ops = {
+    .read = flash_read,
     .write = flash_write,
     .valid.min_access_size = 4,
     .valid.max_access_size = 4,
-- 
2.26.2