APPLIED: [SRU][J][PATCH 0/1] build failure when CONFIG_NET_SWITCHDEV=n (CVE-2024-26837 follow-up)

[Mehmet Basaran]

Applied to jammy:linux master-next branch.

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Koichiro Den <koichiro.den at canonical.com> writes:

> BugLink: https://bugs.launchpad.net/bugs/2104380
>
> [ Impact ]
>
> Since jammy:linux commit 0158242f01a0 ("net: bridge: switchdev: Skip MDB
> replays of deferred events on offload"), the kernel build fails when
> CONFIG_NET_SWITCHDEV=n, as observed in e.g. jammy:linux-kvm. The error is
> as follows:
>
> /build/jammy/net/bridge/br_mdb.c: In function 'br_mdb_queue_one':
> /build/jammy/net/bridge/br_mdb.c:640:13: error: implicit declaration of function
> 'switchdev_port_obj_act_is_deferred'; did you mean 'switchdev_port_obj_add'? \
>   [-Werror=implicit- function-declaration]
>   640 |             switchdev_port_obj_act_is_deferred(dev, action, &mdb.obj)) {
>       |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       |             switchdev_port_obj_add
>
> [ Fix ]
>
> Add a dummy implementation of switchdev_port_obj_act_is_deferred() for the
> CONFIG_NET_SWITCHDEV=n case. This approach was chosen because it is less
> risky and also requires minimal changes compared to the alternatives:
>
> * Backport 9776457c784f ("net: bridge: mdb: move all switchdev logic to
>   br_switchdev.c"), which would involve resolving significant conflicts, or
> * Revert the CVE fix, cherry-pick nearly all prerequisite patches from [1]
>   and [2], and then reapply the CVE fix.
>
> Note that register_switchdev_blocking_notifier() does nothing when
> CONFIG_NET_SWITCHDEV=n. Therefore, nbp_switchdev_(un)sync_objs (the sole
> caller of br_mdb_replay()) does not run in the first place.
>
> [1] https://lore.kernel.org/all/20211026142743.1298877-1-vladimir.oltean@nxp.com/
> [2] https://lore.kernel.org/all/20211027162119.2496321-1-vladimir.oltean@nxp.com/
>
> [ Test Plan ]
>
> Compile test with both CONFIG_NET_SWITCHDEV=y and CONFIG_NET_SWITCHDEV=n.
>
> [ Where problems could occur ]
>
> Any regressions caused by this tiny fix-the-fix patch should be caught
> during compilation.
>
>
> Koichiro Den (1):
>   UBUNTU: SAUCE: net: switchdev: fix compilation error for
>     CONFIG_NET_SWITCHDEV=n
>
>  include/net/switchdev.h | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> -- 
> 2.45.2
>
>
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
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