[PATCH net] ionic: catch NULL pointer issue on reconfig

[PATCH net] ionic: catch NULL pointer issue on reconfig

[Shannon Nelson]

From: Brett Creeley <brett@pensando.io>

It's possible that the driver will dereference a qcq that doesn't exist
when calling ionic_reconfigure_queues(), which causes a page fault BUG.

If a reduction in the number of queues is followed by a different
reconfig such as changing the ring size, the driver can hit a NULL
pointer when trying to clean up non-existent queues.

Fix this by checking to make sure both the qcqs array and qcq entry
exists bofore trying to use and free the entry.

Fixes: 101b40a0171f ("ionic: change queue count with no reset")
Signed-off-by: Brett Creeley <brett@pensando.io>
Signed-off-by: Shannon Nelson <snelson@pensando.io>
---
 drivers/net/ethernet/pensando/ionic/ionic_lif.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.c b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
index 5d58fd99be3c..19d4848df17d 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
@@ -2817,11 +2817,15 @@ int ionic_reconfigure_queues(struct ionic_lif *lif,
 	 * than the full array, but leave the qcq shells in place
 	 */
 	for (i = lif->nxqs; i < lif->ionic->ntxqs_per_lif; i++) {
-		lif->txqcqs[i]->flags &= ~IONIC_QCQ_F_INTR;
-		ionic_qcq_free(lif, lif->txqcqs[i]);
+		if (lif->txqcqs && lif->txqcqs[i]) {
+			lif->txqcqs[i]->flags &= ~IONIC_QCQ_F_INTR;
+			ionic_qcq_free(lif, lif->txqcqs[i]);
+		}
 
-		lif->rxqcqs[i]->flags &= ~IONIC_QCQ_F_INTR;
-		ionic_qcq_free(lif, lif->rxqcqs[i]);
+		if (lif->rxqcqs && lif->rxqcqs[i]) {
+			lif->rxqcqs[i]->flags &= ~IONIC_QCQ_F_INTR;
+			ionic_qcq_free(lif, lif->rxqcqs[i]);
+		}
 	}
 
 	if (err)
-- 
2.17.1

Re: [PATCH net] ionic: catch NULL pointer issue on reconfig

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 17 Oct 2022 16:31:23 -0700 you wrote:
> From: Brett Creeley <brett@pensando.io>
> 
> It's possible that the driver will dereference a qcq that doesn't exist
> when calling ionic_reconfigure_queues(), which causes a page fault BUG.
> 
> If a reduction in the number of queues is followed by a different
> reconfig such as changing the ring size, the driver can hit a NULL
> pointer when trying to clean up non-existent queues.
> 
> [...]

Here is the summary with links:
  - [net] ionic: catch NULL pointer issue on reconfig
    https://git.kernel.org/netdev/net/c/aa1d7e1267c1

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html