Re: [PATCH 2/3] KVM: Stop looking for coalesced MMIO zones if the bus is destroyed

[Jim Mattson]

On Mon, Apr 12, 2021 at 3:21 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>
> Abort the walk of coalesced MMIO zones if kvm_io_bus_unregister_dev()
> fails to allocate memory for the new instance of the bus.  If it can't
> instantiate a new bus, unregister_dev() destroys all devices _except_ the
> target device.   But, it doesn't tell the caller that it obliterated the
> bus and invoked the destructor for all devices that were on the bus.  In
> the coalesced MMIO case, this can result in a deleted list entry
> dereference due to attempting to continue iterating on coalesced_zones
> after future entries (in the walk) have been deleted.
>
> Opportunistically add curly braces to the for-loop, which encompasses
> many lines but sneaks by without braces due to the guts being a single
> if statement.
>
> Fixes: f65886606c2d ("KVM: fix memory leak in kvm_io_bus_unregister_dev()")
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Hao Sun <sunhao.th@xxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>