Re: [libvirt] [PATCH] virpcitest: fix coverity issues
On 6.2.2014 16:48, Eric Blake wrote:
On 02/06/2014 08:18 AM, Pavel Hrdina wrote:
> The coverity server complains about the dev->stubDriver that it was
> freed by the virPCIDeviceSetStubDriver function, but it somehow don't
> get the fact that into the variable is immediately assigned new string.
>
> Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com>
> ---
> tests/virpcitest.c | 2 ++
> 1 file changed, 2 insertions(+)
What's the exact complaint?
The first one that coverity don't get that after free the new string is
assigned into the dev->stubDriver:
--------------------------------------------------------------------
Event freed_arg: "virPCIDeviceSetStubDriver" frees
"dev->stubDriver".
--------------------------------------------------------------------
This is the root cause for another complaint that the dev->stubDriver is
dereferenced after free:
--------------------------------------------------------------------
Event deref_arg: Calling "virPCIDeviceDetach" dereferences freed
pointer "dev->stubDriver".
--------------------------------------------------------------------
>
> diff --git a/tests/virpcitest.c b/tests/virpcitest.c
> index 994b300..8ff3b1d 100644
> --- a/tests/virpcitest.c
> +++ b/tests/virpcitest.c
> @@ -248,6 +248,7 @@ testVirPCIDeviceDetachSingle(const void *opaque)
> if (!dev)
> goto cleanup;
>
> + /* coverity[freed_arg] */
> if (virPCIDeviceSetStubDriver(dev, "pci-stub") < 0 ||
> virPCIDeviceDetach(dev, NULL, NULL) < 0)
> goto cleanup;
Is this something where an sa_assert() could do the trick in a more
tool-agnostic manner?
I'm looking at the code again and probably the issue found by coverity
could happen if the STRDUP fails inside of the
virPCIDeviceSetStubDriver.
This is a corner case where it could leads to creating a wrong modprobe
command because the dev->stubDriver also as driver and then as module
wouldn't be included in the command line.
--------------------------------------------------------------------
virPCIDeviceDetach()->virPCIProbeStubDriver()->virKModLoad()->
doModprobe()
--------------------------------------------------------------------
For the virKmodLoad() function the coverity found this issue:
--------------------------------------------------------------------
Event deref_parm_in_call: Function "virKModLoad" dereferences
"driver". (The dereference is assumed on the basis of the 'nonnull'
parameter attribute.)
--------------------------------------------------------------------
I'm not sure what to do with this. At first I've thought that it's only
the coverity mistake.
Thanks for the review,
Pavel