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Date:   Tue, 3 Jul 2018 15:53:25 -0600
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Neil Horman <nhorman@tuxdriver.com>
Cc:     linux-rdma@vger.kernel.org, Adit Ranadive <aditr@vmware.com>,
        VMware PV-Drivers <pv-drivers@vmware.com>,
        Doug Ledford <dledford@redhat.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] vmw_pvrdma: Release netdev when vmxnet3 module is
 removed
Message-ID: <20180703215325.GA29072@ziepe.ca>
References: <20180628135938.19625-1-nhorman@tuxdriver.com>
 <20180629115206.18787-1-nhorman@tuxdriver.com>
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On Fri, Jun 29, 2018 at 07:52:06AM -0400, Neil Horman wrote:
> On repeated module load/unload cycles, its possible for the pvrmda
> driver to encounter this crash:
> 
> ...
> 297.032448] RIP: 0010:[<ffffffff839e4620>]  [<ffffffff839e4620>] netdev_walk_all_upper_dev_rcu+0x50/0xb0
> [  297.034078] RSP: 0018:ffff95087780bd08  EFLAGS: 00010286
> [  297.034986] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff95087a0c0000
> [  297.036196] RDX: ffff95087a0c0000 RSI: ffffffff839e44e0 RDI: ffff950835d0c000
> [  297.037421] RBP: ffff95087780bd40 R08: ffff95087a0e0ea0 R09: abddacd03f8e0ea0
> [  297.038636] R10: abddacd03f8e0ea0 R11: ffffef5901e9dbc0 R12: ffff95087a0c0000
> [  297.039854] R13: ffffffff839e44e0 R14: ffff95087a0c0000 R15: ffff950835d0c828
> [  297.041071] FS:  0000000000000000(0000) GS:ffff95087fc00000(0000) knlGS:0000000000000000
> [  297.042443] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  297.043429] CR2: ffffffffffffffe8 CR3: 000000007a652000 CR4: 00000000003607f0
> [  297.044674] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [  297.045893] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [  297.047109] Call Trace:
> [  297.047545]  [<ffffffff839e4698>] netdev_has_upper_dev_all_rcu+0x18/0x20
> [  297.048691]  [<ffffffffc05d31af>] is_eth_port_of_netdev+0x2f/0xa0 [ib_core]
> [  297.049886]  [<ffffffffc05d3180>] ? is_eth_active_slave_of_bonding_rcu+0x70/0x70 [ib_core]
> ...
> 
> This occurs because vmw_pvrdma on probe stores a pointer to the netdev
> that exists on function 0 of the same bus/device/slot (which represents
> the vmxnet3 ethernet driver).  However, it never removes this pointer if
> the vmxnet3 module is removed, leading to crashes resulting from use
> after free dereferencing incidents like the one above.
> 
> The fix is pretty straightforward.  vmw_pvrdma should listen for
> NETDEV_REGISTER and NETDEV_UNREGISTER events in its event listener code
> block, and update the stored netdev pointer accordingly.  This solution
> has been tested by myself and the reporter with successful results.
> This fix also allows the pvrdma driver to find its underlying ethernet
> device in the event that vmxnet3 is loaded after pvrdma, which it was
> not able to do before.
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> Reported-by: ruquin@redhat.com
> CC: Adit Ranadive <aditr@vmware.com>
> CC: VMware PV-Drivers <pv-drivers@vmware.com>
> CC: Doug Ledford <dledford@redhat.com>
> CC: Jason Gunthorpe <jgg@ziepe.ca>
> CC: linux-kernel@vger.kernel.org
> Tested-by: Adit Ranadive <aditr@vmware.com>
> Acked-by: Adit Ranadive <aditr@vmware.com>
> ---
> Change notes
> 
> v2)
>  * Move dev_hold in pvrda_pci_probe to below null check (aditr)
>  * Add dev_puts to probe error path and pvrda_pci_remove (jgg)
>  * Cleaned up some checkpatch warnings (nhorman)
> ---
>  .../infiniband/hw/vmw_pvrdma/pvrdma_main.c    | 39 ++++++++++++++++++-
>  1 file changed, 37 insertions(+), 2 deletions(-)

Appled to for-next

Thanks,
Jason