Re: [PATCH net 1/2] iavf: Fix use-after-free in free_netdev

[Ding Hui]

On 2023/4/19 0:02, Michal Kubiak wrote:
> On Sat, Apr 08, 2023 at 10:00:29PM +0800, Ding Hui wrote:
> > We do netif_napi_add() for all allocated q_vectors[], but potentially
> > do netif_napi_del() for part of them, then kfree q_vectors and lefted
> > invalid pointers at dev->napi_list.
> >
> > If num_active_queues is changed to less than allocated q_vectors[] by
> > by unexpected, when iavf_remove, we might see UAF in free_netdev like this:
>
> Nitpick: the word "by" is accidentally doubled.

Oops, I noticed too, and I'll update in v2.

> Also, I would recommend to add a description of reproduction steps (most
> preferably a script or a command sequence) which triggers such an error
> reported by KASAN.

Sure, I'll update in v2.

> > [ 4093.900222] ==================================================================
> > [ 4093.900230] BUG: KASAN: use-after-free in free_netdev+0x308/0x390
> > [ 4093.900232] Read of size 8 at addr ffff88b4dc145640 by task test-iavf-1.sh/6699
> > [ 4093.900233]
> > [ 4093.900236] CPU: 10 PID: 6699 Comm: test-iavf-1.sh Kdump: loaded Tainted: G           O     --------- -t - 4.18.0 #1
> > [ 4093.900238] Hardware name: Powerleader PR2008AL/H12DSi-N6, BIOS 2.0 04/09/2021
> > [ 4093.900239] Call Trace:
> > [ 4093.900244]  dump_stack+0x71/0xab
> > [ 4093.900249]  print_address_description+0x6b/0x290
> > [ 4093.900251]  ? free_netdev+0x308/0x390
> > [ 4093.900252]  kasan_report+0x14a/0x2b0
> > [ 4093.900254]  free_netdev+0x308/0x390
> > [ 4093.900261]  iavf_remove+0x825/0xd20 [iavf]
> > [ 4093.900265]  pci_device_remove+0xa8/0x1f0
> > [ 4093.900268]  device_release_driver_internal+0x1c6/0x460
> > [ 4093.900271]  pci_stop_bus_device+0x101/0x150
> > [ 4093.900273]  pci_stop_and_remove_bus_device+0xe/0x20
> > [ 4093.900275]  pci_iov_remove_virtfn+0x187/0x420
> > [ 4093.900277]  ? pci_iov_add_virtfn+0xe10/0xe10
> > [ 4093.900278]  ? pci_get_subsys+0x90/0x90
> > [ 4093.900280]  sriov_disable+0xed/0x3e0
> > [ 4093.900282]  ? bus_find_device+0x12d/0x1a0
> > [ 4093.900290]  i40e_free_vfs+0x754/0x1210 [i40e]
> > [ 4093.900298]  ? i40e_reset_all_vfs+0x880/0x880 [i40e]
> > [ 4093.900299]  ? pci_get_device+0x7c/0x90
> > [ 4093.900300]  ? pci_get_subsys+0x90/0x90
> > [ 4093.900306]  ? pci_vfs_assigned.part.7+0x144/0x210
> > [ 4093.900309]  ? __mutex_lock_slowpath+0x10/0x10
> > [ 4093.900315]  i40e_pci_sriov_configure+0x1fa/0x2e0 [i40e]
> > [ 4093.900318]  sriov_numvfs_store+0x214/0x290
> > [ 4093.900320]  ? sriov_totalvfs_show+0x30/0x30
> > [ 4093.900321]  ? __mutex_lock_slowpath+0x10/0x10
> > [ 4093.900323]  ? __check_object_size+0x15a/0x350
> > [ 4093.900326]  kernfs_fop_write+0x280/0x3f0
> > [ 4093.900329]  vfs_write+0x145/0x440
> > [ 4093.900330]  ksys_write+0xab/0x160
> > [ 4093.900332]  ? __ia32_sys_read+0xb0/0xb0
> > [ 4093.900334]  ? fput_many+0x1a/0x120
> > [ 4093.900335]  ? filp_close+0xf0/0x130
> > [ 4093.900338]  do_syscall_64+0xa0/0x370
> > [ 4093.900339]  ? page_fault+0x8/0x30
> > [ 4093.900341]  entry_SYSCALL_64_after_hwframe+0x65/0xca
> > [ 4093.900357] RIP: 0033:0x7f16ad4d22c0
> > ---
> >   drivers/net/ethernet/intel/iavf/iavf_main.c | 6 +-----
> >   1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
> > index 095201e83c9d..a57e3425f960 100644
> > --- a/drivers/net/ethernet/intel/iavf/iavf_main.c
> > +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
> > @@ -1849,19 +1849,15 @@ static int iavf_alloc_q_vectors(struct iavf_adapter *adapter)
> >   static void iavf_free_q_vectors(struct iavf_adapter *adapter)
> >   {
> >   	int q_idx, num_q_vectors;
> > -	int napi_vectors;
> >   
> >   	if (!adapter->q_vectors)
> >   		return;
> >   
> >   	num_q_vectors = adapter->num_msix_vectors - NONQ_VECS;
> > -	napi_vectors = adapter->num_active_queues;
> >   
> >   	for (q_idx = 0; q_idx < num_q_vectors; q_idx++) {
> >   		struct iavf_q_vector *q_vector = &adapter->q_vectors[q_idx];
> > -
> > -		if (q_idx < napi_vectors)
> > -			netif_napi_del(&q_vector->napi);
> > +		netif_napi_del(&q_vector->napi);
> >   	}
> >   	kfree(adapter->q_vectors);
> >   	adapter->q_vectors = NULL;
>
> The fix looks correct to me.
> We actually call "netif_napi_add()" for all allocated q_vectors unconditionally
> in "iavf_alloc_q_vectors()").

If you don't mind, I'll add Acked-by: tag in v2, thanks.

> Thanks,
> Michal
>
> > --
> > 2.17.1

--
Thanks,
- Ding Hui