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Message-ID: <3fece61c-3cf3-8e0b-f7de-8e61d4ec9037@sangfor.com.cn>
Date:   Wed, 19 Apr 2023 08:50:10 +0800
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Subject: Re: [PATCH net 1/2] iavf: Fix use-after-free in free_netdev
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To:     Michal Kubiak <michal.kubiak@intel.com>
Cc:     davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, intel-wired-lan@lists.osuosl.org,
        jesse.brandeburg@intel.com, anthony.l.nguyen@intel.com,
        keescook@chromium.org, grzegorzx.szczurek@intel.com,
        mateusz.palczewski@intel.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
        Donglin Peng <pengdonglin@sangfor.com.cn>,
        Huang Cun <huangcun@sangfor.com.cn>
References: <20230408140030.5769-1-dinghui@sangfor.com.cn>
 <20230408140030.5769-2-dinghui@sangfor.com.cn>
 <ZD6/H9DotpfOxr1+@localhost.localdomain>
From:   Ding Hui <dinghui@sangfor.com.cn>
In-Reply-To: <ZD6/H9DotpfOxr1+@localhost.localdomain>
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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