On Wed, Mar 20, 2019 at 11:31:57AM +0100, Michal Privoznik wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1686927

When trying to create a nwfilter binding via
nwfilterBindingCreateXML() we may encounter a crash. The sequence
of functions called is as follows:

1) nwfilterBindingCreateXML() parses the XML and calls
virNWFilterBindingObjListAdd() which calls
virNWFilterBindingObjListAddLocked()

2) Here, @binding is not found because binding->remove is set.

3) Therefore, controls continue with creating new @binding,
setting its def to the one from 1) and adding it to the hash
table.

4) This fails, because the binding is still in the hash table
(duplicate key is detected).

5) The control jumps to 'error' label where
virNWFilterBindingObjEndAPI() is called which frees the binding
definition passed.

6) Error is propagated to the caller, which calls
virNWFilterBindingDefFree() over the definition again.

The solution is to unset binding->def in case of failure so it's
not freed in step 5).

Signed-off-by: Michal Privoznik <[email protected]>
---

Technically, this is a v2 of:

https://www.redhat.com/archives/libvir-list/2019-March/msg01209.html

But since this one implements different approach than v1 I'm not marking
it as such.

src/conf/virnwfilterbindingobj.c     | 10 ++++++++++
src/conf/virnwfilterbindingobj.h     |  3 +++
src/conf/virnwfilterbindingobjlist.c |  4 ++++
src/libvirt_private.syms             |  1 +
4 files changed, 18 insertions(+)


Reviewed-by: Ján Tomko <[email protected]>

Jano

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