[PATCH net] enetc: Fix illegal access when reading affinity_hint

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@nxp.com>
---
 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 3ca93adb9662..7f90c27c0e79 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c

@@ -1879,7 +1879,6 @@ 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++) {

@@ -1908,9 +1907,7 @@ 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;

-- 
2.25.1

The only struct dim_sample member that does not get
initialized by dim_update_sample() is comp_ctr. (There
is special API to initialize comp_ctr:
dim_update_sample_with_comps(), and it is currently used
only for RDMA.) comp_ctr is used to compute curr_stats->cmps
and curr_stats->cpe_ratio (see dim_calc_stats()) which in
turn are consumed by the rdma_dim_*() API.  Therefore,
functionally, the net_dim*() API consumers are not affected.
Nevertheless, fix the computation of statistics based
on an uninitialized variable, even if the mentioned statistics
are not used at the moment.

Fixes: ae0e6a5d1627 ("enetc: Add adaptive interrupt coalescing")
Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
---
 drivers/net/ethernet/freescale/enetc/enetc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index 7f90c27c0e79..042327b9981f 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c

@@ -419,7 +419,7 @@ static void enetc_rx_dim_work(struct work_struct *w)
 
 static void enetc_rx_net_dim(struct enetc_int_vector *v)
 {
-	struct dim_sample dim_sample;
+	struct dim_sample dim_sample = {};
 
 	v->comp_cnt++;
 

-- 
2.25.1

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Fri, 17 Sep 2021 13:22:06 +0300 you wrote:

The only struct dim_sample member that does not get
initialized by dim_update_sample() is comp_ctr. (There
is special API to initialize comp_ctr:
dim_update_sample_with_comps(), and it is currently used
only for RDMA.) comp_ctr is used to compute curr_stats->cmps
and curr_stats->cpe_ratio (see dim_calc_stats()) which in
turn are consumed by the rdma_dim_*() API.  Therefore,
functionally, the net_dim*() API consumers are not affected.
Nevertheless, fix the computation of statistics based
on an uninitialized variable, even if the mentioned statistics
are not used at the moment.

[...]

Here is the summary with links:
  - [net] enetc: Fix uninitialized struct dim_sample field usage
    https://git.kernel.org/netdev/net/c/9f7afa05c952

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

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Fri, 17 Sep 2021 13:22:05 +0300 you wrote:

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.

[...]

Here is the summary with links:
  - [net] enetc: Fix illegal access when reading affinity_hint
    https://git.kernel.org/netdev/net/c/7237a494decf

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