[libvirt] [PATCH] virpci: Resolve coverity issues

[John Ferlan]

Coverity complains about "USE_AFTER_FREE" due to how virPCIDeviceSetStubDriver
"could" return either -1, 0, or 1 from the VIR_STRDUP() and then possibly makes
a call to virPCIDeviceDetach().

The only way this could happen is if NULL were passed as the "driver" name
and virStrdup() returned 0.  Since the calling functions check < 0 on the
initial function call, the 0 possibility causes Coverity to complain.

To fix this - enforce that the second parameter is not NULL using
ATTRIBUTE_NONNULL(2) for the function prototype, then in virPCIDeviceDetach
add an sa_assert(dev->stubDriver). This will result in Coverity not complaining
any more.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---

NOTE: This replaces Pavel's patch posted yesterday:

http://www.redhat.com/archives/libvir-list/2014-February/msg00319.html


 src/util/virpci.c | 4 +++-
 src/util/virpci.h | 3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/util/virpci.c b/src/util/virpci.c
index c3d211f..00d1064 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -1327,6 +1327,8 @@ virPCIDeviceDetach(virPCIDevicePtr dev,
                    virPCIDeviceList *activeDevs,
                    virPCIDeviceList *inactiveDevs)
 {
+    sa_assert(dev->stubDriver);
+
     if (virPCIProbeStubDriver(dev->stubDriver) < 0)
         return -1;
 
@@ -1657,7 +1659,7 @@ int
 virPCIDeviceSetStubDriver(virPCIDevicePtr dev, const char *driver)
 {
     VIR_FREE(dev->stubDriver);
-    return driver ? VIR_STRDUP(dev->stubDriver, driver) : 0;
+    return VIR_STRDUP(dev->stubDriver, driver);
 }
 
 const char *
diff --git a/src/util/virpci.h b/src/util/virpci.h
index 42c3c95..ac6dae1 100644
--- a/src/util/virpci.h
+++ b/src/util/virpci.h
@@ -63,7 +63,8 @@ void virPCIDeviceSetManaged(virPCIDevice *dev,
                             bool managed);
 unsigned int virPCIDeviceGetManaged(virPCIDevice *dev);
 int virPCIDeviceSetStubDriver(virPCIDevicePtr dev,
-                              const char *driver);
+                              const char *driver)
+    ATTRIBUTE_NONNULL(2);
 const char *virPCIDeviceGetStubDriver(virPCIDevicePtr dev);
 void virPCIDeviceSetUsedBy(virPCIDevice *dev,
                            const char *used_by);
-- 
1.8.4.2