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

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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