qdev_get_clocklist() function returns a pointer to the NamedClockList
struct. This function is called in qdev_alias_clock() and the returned
pointer is immediately dereferenced without a null check.

Passing clock name that doesn't exist to qdev_get_clocklist() is a
programming error, and so this change is not fixing a bug, only making
the reporting of that programming error a bit more helpful and bringing
it in to line with qdev_get_clock_in() and qdev_get_clock_out().

Cc: luc@lmichel.fr
Cc: peter.maydell@linaro.org
Cc: hemanshu_dev@proton.me
Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/2342
Signed-off-by: hemanshu.khilari.foss <hemanshu.khilari.foss@gmail.com>
---
 hw/core/qdev-clock.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/core/qdev-clock.c b/hw/core/qdev-clock.c
index 6e2967e433..861f78f94c 100644
--- a/hw/core/qdev-clock.c
+++ b/hw/core/qdev-clock.c
@@ -157,7 +157,14 @@ Clock *qdev_alias_clock(DeviceState *dev, const char *name,
                         DeviceState *alias_dev, const char *alias_name)
 {
     NamedClockList *ncl = qdev_get_clocklist(dev, name);
-    Clock *clk = ncl->clock;
+    Clock *clk;
+
+    if (!ncl) {
+        error_report("Can not find clock '%s' for device type '%s'",
+                     name, object_get_typename(OBJECT(dev)));
+        abort();
+    }
+    clk = ncl->clock;
 
     ncl = qdev_init_clocklist(alias_dev, alias_name, true, ncl->output, clk);
 
-- 
2.42.0