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From: "Philippe Mathieu-Daudé" <philmd@linaro.org>
To: qemu-devel@nongnu.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Jens Freimann" <jfreimann@redhat.com>,
	"Eduardo Habkost" <eduardo@habkost.net>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	"Peter Maydell" <peter.maydell@linaro.org>
Subject: [PATCH] system/qdev: Remove pointless NULL check in qdev_device_add_from_qdict
Date: Mon, 10 Feb 2025 13:10:45 +0100	[thread overview]
Message-ID: <20250210121045.38908-1-philmd@linaro.org> (raw)

Coverity reported a unnecessary NULL check:

  qemu/system/qdev-monitor.c: 720 in qdev_device_add_from_qdict()
  683     /* create device */
  684     dev = qdev_new(driver);
  ...
  719     err_del_dev:
  >>>     CID 1590192:  Null pointer dereferences  (REVERSE_INULL)
  >>>     Null-checking "dev" suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
  720         if (dev) {
  721             object_unparent(OBJECT(dev));
  722             object_unref(OBJECT(dev));
  723         }
  724         return NULL;
  725     }

Indeed, unlike qdev_try_new() which can return NULL,
qdev_new() always returns a heap pointer (or aborts).

Remove the unnecessary assignment and check.

Fixes: f3a85056569 ("qdev/qbus: add hidden device support")
Resolves: Coverity CID 1590192 (Null pointer dereferences)
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 system/qdev-monitor.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/system/qdev-monitor.c b/system/qdev-monitor.c
index 861c25c855f..01d4b007322 100644
--- a/system/qdev-monitor.c
+++ b/system/qdev-monitor.c
@@ -628,7 +628,7 @@ DeviceState *qdev_device_add_from_qdict(const QDict *opts,
     DeviceClass *dc;
     const char *driver, *path;
     char *id;
-    DeviceState *dev = NULL;
+    DeviceState *dev;
     BusState *bus = NULL;
     QDict *properties;
 
@@ -717,10 +717,9 @@ DeviceState *qdev_device_add_from_qdict(const QDict *opts,
     return dev;
 
 err_del_dev:
-    if (dev) {
-        object_unparent(OBJECT(dev));
-        object_unref(OBJECT(dev));
-    }
+    object_unparent(OBJECT(dev));
+    object_unref(OBJECT(dev));
+
     return NULL;
 }
 
-- 
2.47.1



             reply	other threads:[~2025-02-10 12:11 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-10 12:10 Philippe Mathieu-Daudé [this message]
2025-02-10 17:07 ` [PATCH] system/qdev: Remove pointless NULL check in qdev_device_add_from_qdict Richard Henderson
2025-07-10 14:48 ` Peter Maydell
2025-07-16  3:34   ` Philippe Mathieu-Daudé

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