Re: [PATCH 5.4/5.10 1/1] RDMA/i40iw: Fix potential NULL-ptr-dereference

[Nikita Zhandarovich <n.zhandarovich@fintech.ru>]

On 3/15/23 01:00, Greg Kroah-Hartman wrote:
> On Tue, Mar 14, 2023 at 06:44:56AM -0700, Nikita Zhandarovich wrote:
>> From: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
>>
>> commit 5d9745cead1f121974322b94ceadfb4d1e67960e upstream.
>>
>> in_dev_get() can return NULL which will cause a failure once idev is
>> dereferenced in in_dev_for_each_ifa_rtnl(). This patch adds a
>> check for NULL value in idev beforehand.
>>
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>
>> Changes made to the original patch during backporting:
>> Apply patch to drivers/infiniband/hw/i40iw/i40iw_cm.c instead of
>> drivers/infiniband/hw/irdma/cm.c due to the fact that kernel versions
>> 5.10 and below use i40iw driver, not irdma.
>>
>> Fixes: f27b4746f378 ("i40iw: add connection management code")
>> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
>> Link: https://lore.kernel.org/r/20230126185230.62464-1-n.zhandarovich@fintech.ru
>> ---
>>  drivers/infiniband/hw/i40iw/i40iw_cm.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/infiniband/hw/i40iw/i40iw_cm.c b/drivers/infiniband/hw/i40iw/i40iw_cm.c
>> index 3053c345a5a3..e1236ac502f2 100644
>> --- a/drivers/infiniband/hw/i40iw/i40iw_cm.c
>> +++ b/drivers/infiniband/hw/i40iw/i40iw_cm.c
>> @@ -1776,6 +1776,8 @@ static enum i40iw_status_code i40iw_add_mqh_4(
>>  			const struct in_ifaddr *ifa;
>>  
>>  			idev = in_dev_get(dev);
>> +			if (!idev)
>> +				continue;
>>  
>>  			in_dev_for_each_ifa_rtnl(ifa, idev) {
>>  				i40iw_debug(&iwdev->sc_dev,
> 
> As this isn't anything that can be triggered by a normal system
> operation, I'm going to drop it from the review queue.  Unless you have
> a reproducer that can cause this to happen from userspace?
> 
> thanks,
> 
> greg k-h

Currently working on seeing whether a reproducer is feasible. It makes
sense to not include the patch until then.

thanks for your time,

Nikita