[libvirt PATCH] nodedev: Fix possible NULL pointer dereference on vfiogroup opening

[Ján Tomko]

On a Tuesday in 2021, Erik Skultety wrote:
>Coverity report:
>    1193    g_autofree char *vfiogroup =
>    1194        virMediatedDeviceGetIOMMUGroupDev(def->caps->data.mdev.uuid);
>
>    >>> CID 317619:  Null pointer dereferences  (NULL_RETURNS)
>    >>> Dereferencing a pointer that might be "NULL" "vfiogroup" when
>        calling "open". [Note: The source code implementation of the
>        function has been overridden by a builtin model.]
>
>    1195    VIR_AUTOCLOSE fd = open(vfiogroup, O_RDONLY);
>
>This patch shuffles the declarations in the affected 'if' block a bit
>to make it more readable after adding the NULL pointer condition.
>
>Note that error is not reported in this patch, because if @vfiogroup
>is NULL, then it must have been a system error which was already
>reported by the called function. Don't get confused by
>virMediatedDeviceGetIOMMUGroupDev returning NULL on an empty UUID,
>mdevs will always have one.
>
>Signed-off-by: Erik Skultety <eskultet at redhat.com>
>---
> src/node_device/node_device_driver.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>

Just for the record, almost identical patch was merged as:

commit 5c4b2bf7709ef517502fccdf3d92b166f8f82ba4
Author:     Jonathon Jongsma <jjongsma at redhat.com>
CommitDate: 2021-04-15 08:51:37 -0500

     nodedev: handle null return from GetIOMMUGroupDev()

from a different series.

Jano
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