[PATCH 5.4 27/68] enetc: Fix illegal access when reading affinity_hint

From: Greg Kroah-Hartman
Date: Mon Sep 27 2021 - 13:05:20 EST

From: Claudiu Manoil <claudiu.manoil@xxxxxxx>

[ Upstream commit 7237a494decfa17d0b9d0076e6cee3235719de90 ]

irq_set_affinity_hit() stores a reference to the cpumask_t
parameter in the irq descriptor, and that reference can be
accessed later from irq_affinity_hint_proc_show(). Since
the cpu_mask parameter passed to irq_set_affinity_hit() has
only temporary storage (it's on the stack memory), later
accesses to it are illegal. Thus reads from the corresponding
procfs affinity_hint file can result in paging request oops.

The issue is fixed by the get_cpu_mask() helper, which provides
a permanent storage for the cpumask_t parameter.

Fixes: d4fd0404c1c9 ("enetc: Introduce basic PF and VF ENETC ethernet drivers")
Signed-off-by: Claudiu Manoil <claudiu.manoil@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/net/ethernet/freescale/enetc/enetc.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index b77eaf31bd4e..cee77326e7e8 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c
@@ -1222,7 +1222,6 @@ static void enetc_clear_bdrs(struct enetc_ndev_priv *priv)
static int enetc_setup_irqs(struct enetc_ndev_priv *priv)
struct pci_dev *pdev = priv->si->pdev;
- cpumask_t cpu_mask;
int i, j, err;

for (i = 0; i < priv->bdr_int_num; i++) {
@@ -1249,9 +1248,7 @@ static int enetc_setup_irqs(struct enetc_ndev_priv *priv)

enetc_wr(hw, ENETC_SIMSITRV(idx), entry);
- cpumask_clear(&cpu_mask);
- cpumask_set_cpu(i % num_online_cpus(), &cpu_mask);
- irq_set_affinity_hint(irq, &cpu_mask);
+ irq_set_affinity_hint(irq, get_cpu_mask(i % num_online_cpus()));

return 0;