| From dcf4ff7a48e7598e6b10126cc02177abb8ae4f3f Mon Sep 17 00:00:00 2001 |
| From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= |
| <marmarek@invisiblethingslab.com> |
| Date: Wed, 23 Feb 2022 22:19:54 +0100 |
| Subject: xen/netfront: destroy queues before real_num_tx_queues is zeroed |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| From: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> |
| |
| commit dcf4ff7a48e7598e6b10126cc02177abb8ae4f3f upstream. |
| |
| xennet_destroy_queues() relies on info->netdev->real_num_tx_queues to |
| delete queues. Since d7dac083414eb5bb99a6d2ed53dc2c1b405224e5 |
| ("net-sysfs: update the queue counts in the unregistration path"), |
| unregister_netdev() indirectly sets real_num_tx_queues to 0. Those two |
| facts together means, that xennet_destroy_queues() called from |
| xennet_remove() cannot do its job, because it's called after |
| unregister_netdev(). This results in kfree-ing queues that are still |
| linked in napi, which ultimately crashes: |
| |
| BUG: kernel NULL pointer dereference, address: 0000000000000000 |
| #PF: supervisor read access in kernel mode |
| #PF: error_code(0x0000) - not-present page |
| PGD 0 P4D 0 |
| Oops: 0000 [#1] PREEMPT SMP PTI |
| CPU: 1 PID: 52 Comm: xenwatch Tainted: G W 5.16.10-1.32.fc32.qubes.x86_64+ #226 |
| RIP: 0010:free_netdev+0xa3/0x1a0 |
| Code: ff 48 89 df e8 2e e9 00 00 48 8b 43 50 48 8b 08 48 8d b8 a0 fe ff ff 48 8d a9 a0 fe ff ff 49 39 c4 75 26 eb 47 e8 ed c1 66 ff <48> 8b 85 60 01 00 00 48 8d 95 60 01 00 00 48 89 ef 48 2d 60 01 00 |
| RSP: 0000:ffffc90000bcfd00 EFLAGS: 00010286 |
| RAX: 0000000000000000 RBX: ffff88800edad000 RCX: 0000000000000000 |
| RDX: 0000000000000001 RSI: ffffc90000bcfc30 RDI: 00000000ffffffff |
| RBP: fffffffffffffea0 R08: 0000000000000000 R09: 0000000000000000 |
| R10: 0000000000000000 R11: 0000000000000001 R12: ffff88800edad050 |
| R13: ffff8880065f8f88 R14: 0000000000000000 R15: ffff8880066c6680 |
| FS: 0000000000000000(0000) GS:ffff8880f3300000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: 0000000000000000 CR3: 00000000e998c006 CR4: 00000000003706e0 |
| Call Trace: |
| <TASK> |
| xennet_remove+0x13d/0x300 [xen_netfront] |
| xenbus_dev_remove+0x6d/0xf0 |
| __device_release_driver+0x17a/0x240 |
| device_release_driver+0x24/0x30 |
| bus_remove_device+0xd8/0x140 |
| device_del+0x18b/0x410 |
| ? _raw_spin_unlock+0x16/0x30 |
| ? klist_iter_exit+0x14/0x20 |
| ? xenbus_dev_request_and_reply+0x80/0x80 |
| device_unregister+0x13/0x60 |
| xenbus_dev_changed+0x18e/0x1f0 |
| xenwatch_thread+0xc0/0x1a0 |
| ? do_wait_intr_irq+0xa0/0xa0 |
| kthread+0x16b/0x190 |
| ? set_kthread_struct+0x40/0x40 |
| ret_from_fork+0x22/0x30 |
| </TASK> |
| |
| Fix this by calling xennet_destroy_queues() from xennet_uninit(), |
| when real_num_tx_queues is still available. This ensures that queues are |
| destroyed when real_num_tx_queues is set to 0, regardless of how |
| unregister_netdev() was called. |
| |
| Originally reported at |
| https://github.com/QubesOS/qubes-issues/issues/7257 |
| |
| Fixes: d7dac083414eb5bb9 ("net-sysfs: update the queue counts in the unregistration path") |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/net/xen-netfront.c | 39 +++++++++++++++++++++++---------------- |
| 1 file changed, 23 insertions(+), 16 deletions(-) |
| |
| --- a/drivers/net/xen-netfront.c |
| +++ b/drivers/net/xen-netfront.c |
| @@ -761,6 +761,28 @@ static int xennet_close(struct net_devic |
| return 0; |
| } |
| |
| +static void xennet_destroy_queues(struct netfront_info *info) |
| +{ |
| + unsigned int i; |
| + |
| + for (i = 0; i < info->netdev->real_num_tx_queues; i++) { |
| + struct netfront_queue *queue = &info->queues[i]; |
| + |
| + if (netif_running(info->netdev)) |
| + napi_disable(&queue->napi); |
| + netif_napi_del(&queue->napi); |
| + } |
| + |
| + kfree(info->queues); |
| + info->queues = NULL; |
| +} |
| + |
| +static void xennet_uninit(struct net_device *dev) |
| +{ |
| + struct netfront_info *np = netdev_priv(dev); |
| + xennet_destroy_queues(np); |
| +} |
| + |
| static void xennet_set_rx_rsp_cons(struct netfront_queue *queue, RING_IDX val) |
| { |
| unsigned long flags; |
| @@ -1373,6 +1395,7 @@ static void xennet_poll_controller(struc |
| #endif |
| |
| static const struct net_device_ops xennet_netdev_ops = { |
| + .ndo_uninit = xennet_uninit, |
| .ndo_open = xennet_open, |
| .ndo_stop = xennet_close, |
| .ndo_start_xmit = xennet_start_xmit, |
| @@ -1860,22 +1883,6 @@ error: |
| return err; |
| } |
| |
| -static void xennet_destroy_queues(struct netfront_info *info) |
| -{ |
| - unsigned int i; |
| - |
| - for (i = 0; i < info->netdev->real_num_tx_queues; i++) { |
| - struct netfront_queue *queue = &info->queues[i]; |
| - |
| - if (netif_running(info->netdev)) |
| - napi_disable(&queue->napi); |
| - netif_napi_del(&queue->napi); |
| - } |
| - |
| - kfree(info->queues); |
| - info->queues = NULL; |
| -} |
| - |
| static int xennet_create_queues(struct netfront_info *info, |
| unsigned int *num_queues) |
| { |