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Draft: Drivers: vmbus: Check for channel allocation before looking up relids

Mohamed Gamal Morsy requested to merge mgamal-rh/centos-stream-9:bz2156126 into main

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2156126

Upstream Status: https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git/ (hyperv-fixes branch)

commit  1eb65c8687316c65140b48fad27133d583178e15
Author: Mohammed Gamal <mgamal@redhat.com>
Date:   Fri Feb 17 22:44:11 2023 +0200

    Drivers: vmbus: Check for channel allocation before looking up relids

    relid2channel() assumes vmbus channel array to be allocated when called.
    However, in cases such as kdump/kexec, not all relids will be reset by the host.
    When the second kernel boots and if the guest receives a vmbus interrupt during
    vmbus driver initialization before vmbus_connect() is called, before it finishes,
    or if it fails, the vmbus interrupt service routine is called which in turn calls
    relid2channel() and can cause a null pointer dereference.

    Print a warning and error out in relid2channel() for a channel id that's invalid
    in the second kernel.

    Fixes: 8b6a877c060e ("Drivers: hv: vmbus: Replace the per-CPU channel lists with a global array of channels")

    Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
    Reviewed-by: Dexuan Cui <decui@microsoft.com>
    Link: https://lore.kernel.org/r/20230217204411.212709-1-mgamal@redhat.com
    Signed-off-by: Wei Liu <wei.liu@kernel.org>

Signed-off-by: Mohamed Gamal Morsy mgamal@redhat.com

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