[ovs-dev] [PATCH] bond: Fix using uninitialized 'lacp_fallback_ab_cfg' for 'bond-primary'.

Jeff Squyres (jsquyres) jsquyres at cisco.com
Tue Oct 13 12:58:08 UTC 2020


On Oct 13, 2020, at 6:02 AM, Ilya Maximets <i.maximets at ovn.org> wrote:
> 
> 's->lacp_fallback_ab_cfg' initialized down below in the code, so
> we're using it uninitialized to detect if we need to get 'bond-primary'
> configuration.
> 
> Found by valgrind:
> 
> Conditional jump or move depends on uninitialised value(s)
>    at 0x409114: port_configure_bond (bridge.c:4569)
>    by 0x409114: port_configure (bridge.c:1284)
>    by 0x40F6E6: bridge_reconfigure (bridge.c:917)
>    by 0x411425: bridge_run (bridge.c:3330)
>    by 0x406D84: main (ovs-vswitchd.c:127)
>  Uninitialised value was created by a stack allocation
>    at 0x408C53: port_configure (bridge.c:1190)
> 
> Fix that by moving this code to the point where 'lacp_fallback_ab_cfg'
> already initialized.  Additionally clarified behavior of 'bond-primary'
> in manpages for the fallback to AB case.
> 
> Fixes: b4e50218a0f8 ("bond: Add 'primary' interface concept for active-backup mode.")
> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
> ---
> vswitchd/bridge.c    | 9 ++++-----
> vswitchd/vswitch.xml | 5 ++++-
> 2 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
> index a3e7facd3..a332517bc 100644
> --- a/vswitchd/bridge.c
> +++ b/vswitchd/bridge.c
> @@ -4565,11 +4565,6 @@ port_configure_bond(struct port *port, struct bond_settings *s)
>                   port->name);
>     }
> 
> -    s->primary = NULL;
> -    if (s->balance == BM_AB || s->lacp_fallback_ab_cfg) {
> -        s->primary = smap_get(&port->cfg->other_config, "bond-primary");
> -    }
> -
>     miimon_interval = smap_get_int(&port->cfg->other_config,
>                                    "bond-miimon-interval", 0);
>     if (miimon_interval <= 0) {
> @@ -4596,6 +4591,10 @@ port_configure_bond(struct port *port, struct bond_settings *s)
> 
>     s->lacp_fallback_ab_cfg = smap_get_bool(&port->cfg->other_config,
>                                        "lacp-fallback-ab", false);
> +    s->primary = NULL;
> +    if (s->balance == BM_AB || s->lacp_fallback_ab_cfg) {
> +        s->primary = smap_get(&port->cfg->other_config, "bond-primary");
> +    }

Excellent catch.

>     LIST_FOR_EACH (iface, port_elem, &port->ifaces) {
>         netdev_set_miimon_interval(iface->netdev, miimon_interval);
> diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
> index 07da2ee8c..20decb2db 100644
> --- a/vswitchd/vswitch.xml
> +++ b/vswitchd/vswitch.xml
> @@ -2008,7 +2008,10 @@
>         If a slave interface with this name exists in the bond and
>         is up, it will be made active.  Relevant only when <ref
>         column="other_config" key="bond_mode"/> is
> -        <code>active-backup</code>.
> +        <code>active-backup</code> or if <code>balance-tcp</code> falls back
> +        to <code>active-backup</code> (e.g. LACP negotiation fails and

Super minor nit: "e.g." should be followed by a comma -- "e.g., LACP negotiation ..."

> +        <ref column="other_config" key="lacp-fallback-ab"/> is
> +        <code>true</code>).
>       </column>
> 
>       <group title="Link Failure Detection">
> -- 
> 2.25.4

Acked-by: Jeff Squyres <jsquyres at cisco.com>


-- 
Jeff Squyres
jsquyres at cisco.com



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