Re: [sdl-qemu] [PATCH 0/1] There are no checks, virDomainChrSourceDefNew can return 0

[Peter Krempa <pkrempa@redhat.com>]

CC-ing qemu-devel with a patch solely for libvirt doesn't make sense.

Also 'libvirt-security' list is private and is is intended as a first
contact list for stuff to be embargoed. It makes little sense to include
it when posting to the public 'libvir-list'.

On Thu, Sep 14, 2023 at 09:44:13 +0000, Миронов Сергей Владимирович wrote:
> There are no checks, virDomainChrSourceDefNew can return 0.

s/0/NULL

While very technically true, realistically that can't happen any more.

'virObjectNew' always returns a valid pointer or abort()s, and
VIR_CLASS_NEW can return 0 on programming errors.

Thus this is not a security issue.

> Return value of a function 'virDomainChrSourceDefNew'
> 
> is dereferenced at qemu_hotplug.c without checking for NULL,
> 
> but it is usually checked for this function.

Remove the extra empty lines please.

> 
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> 
> Fixes: 1f85f0967b ("ci: jobs.sh: Add back '--no-suite syntax-check --print-errorlogs'")

^^ This makes no sense. The commit you are referencing is changing a
shell script.

> 
> Signed-off-by: Sergey Mironov <mironov@fintech.ru>
> 
> ---
> src/qemu/qemu_hotplug.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index 177ca87d11..09e16c2c7e 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -3207,6 +3207,8 @@ qemuDomainAttachFSDevice(virQEMUDriver *driver,
>      qemuAssignDeviceFSAlias(vm->def, fs);
> 
>      chardev = virDomainChrSourceDefNew(priv->driver->xmlopt);
> +    if (chardev == NULL)
> +           goto cleanup;
>      chardev->type = VIR_DOMAIN_CHR_TYPE_UNIX;
>      chardev->data.nix.path = qemuDomainGetVHostUserFSSocketPath(priv, fs);
> --
> 2.31.1