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From:   "Raj, Victor" <victor.raj@intel.com>
To:     "G, GurucharanX" <gurucharanx.g@intel.com>,
        "Keller, Jacob E" <jacob.e.keller@intel.com>,
        Xiaomeng Tong <xiam0nd.tong@gmail.com>,
        "Brandeburg, Jesse" <jesse.brandeburg@intel.com>
CC:     "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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        "pabeni@redhat.com" <pabeni@redhat.com>,
        "davem@davemloft.net" <davem@davemloft.net>
Subject: RE: [PATCH] ice: ice_sched: fix an incorrect NULL check on list
 iterator
Thread-Topic: [PATCH] ice: ice_sched: fix an incorrect NULL check on list
 iterator
Thread-Index: AQHYQaYNl8IK5yEFGUm2RVp4aZPsQqzVF96AgDZe+gCAAQZQ4A==
Date:   Tue, 3 May 2022 00:31:28 +0000
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If the control comes down to the loop then surely the VSI is already part o=
f an aggregator (old). The aggregator vsi list should have that VSI informa=
tion. My understanding is that if control comes here then you always find a=
 valid entry and matching handle here. If that doesn't happen then we need =
to debug. The fix is kind of masking this problem.

-Victor


-----Original Message-----
From: G, GurucharanX <gurucharanx.g@intel.com>=20
Sent: Monday, May 2, 2022 1:18 AM
To: Keller, Jacob E <jacob.e.keller@intel.com>; Xiaomeng Tong <xiam0nd.tong=
@gmail.com>; Brandeburg, Jesse <jesse.brandeburg@intel.com>
Cc: netdev@vger.kernel.org; Raj, Victor <victor.raj@intel.com>; stable@vger=
.kernel.org; linux-kernel@vger.kernel.org; intel-wired-lan@lists.osuosl.org=
; kuba@kernel.org; pabeni@redhat.com; davem@davemloft.net
Subject: RE: [PATCH] ice: ice_sched: fix an incorrect NULL check on list it=
erator


-----Original Message-----
> From: Xiaomeng Tong <xiam0nd.tong@gmail.com>
> Sent: Saturday, March 26, 2022 11:44 PM
> To: Brandeburg, Jesse <jesse.brandeburg@intel.com>
> Cc: Nguyen, Anthony L <anthony.l.nguyen@intel.com>;=20
> davem@davemloft.net; kuba@kernel.org; pabeni@redhat.com; Raj, Victor=20
> <victor.raj@intel.com>; intel- wired-lan@lists.osuosl.org;=20
> netdev@vger.kernel.org; linux- kernel@vger.kernel.org; Xiaomeng Tong=20
> <xiam0nd.tong@gmail.com>; stable@vger.kernel.org
> Subject: [PATCH] ice: ice_sched: fix an incorrect NULL check on list=20
> iterator
>
> The bugs are here:
> 	if (old_agg_vsi_info)
> 	if (old_agg_vsi_info && !old_agg_vsi_info->tc_bitmap[0]) {
>
> The list iterator value 'old_agg_vsi_info' will *always* be set and=20
> non-NULL by list_for_each_entry_safe(), so it is incorrect to assume=20
> that the iterator value will be NULL if the list is empty or no=20
> element found (in this case, the check 'if (old_agg_vsi_info)' will=20
> always be true unexpectly).
>
> To fix the bug, use a new variable 'iter' as the list iterator, while=20
> use the original variable 'old_agg_vsi_info' as a dedicated pointer to=20
> point to the found element.
>

Yep. This looks correct to me.

> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
>=20
> Thanks,
> Jake

> Cc: stable@vger.kernel.org
> Fixes: 37c592062b16d ("ice: remove the VSI info from previous agg")
> Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
> ---
>  drivers/net/ethernet/intel/ice/ice_sched.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>

Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Int=
el)