After calling irq_set_affinity_and_hint(), the cpumask pointer is
saved in desc->affinity_hint, and will be used later when reading
/proc/irq/<num>/affinity_hint. So the cpumask variable needs to be
allocated per irq, and available until freeing the irq. Otherwise,
we are accessing freed memory when reading the affinity_hint file.

To fix the bug, allocate the cpumask per irq, and free it just
before freeing the irq.

Cc: stable@vger.kernel.org
Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA nodes")
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 .../net/ethernet/microsoft/mana/gdma_main.c   | 40 ++++++++++---------
 include/net/mana/gdma.h                       |  1 +
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
index 3bae9d4c1f08..37473ae3859c 100644
--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
@@ -1219,7 +1219,6 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
 	struct gdma_irq_context *gic;
 	unsigned int max_irqs;
 	u16 *cpus;
-	cpumask_var_t req_mask;
 	int nvec, irq;
 	int err, i = 0, j;
 
@@ -1240,25 +1239,26 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
 		goto free_irq_vector;
 	}
 
-	if (!zalloc_cpumask_var(&req_mask, GFP_KERNEL)) {
-		err = -ENOMEM;
-		goto free_irq;
-	}
-
 	cpus = kcalloc(nvec, sizeof(*cpus), GFP_KERNEL);
 	if (!cpus) {
 		err = -ENOMEM;
-		goto free_mask;
+		goto free_gic;
 	}
 	for (i = 0; i < nvec; i++)
 		cpus[i] = cpumask_local_spread(i, gc->numa_node);
 
 	for (i = 0; i < nvec; i++) {
-		cpumask_set_cpu(cpus[i], req_mask);
 		gic = &gc->irq_contexts[i];
 		gic->handler = NULL;
 		gic->arg = NULL;
 
+		if (!zalloc_cpumask_var(&gic->cpu_hint, GFP_KERNEL)) {
+			err = -ENOMEM;
+			goto free_irq;
+		}
+
+		cpumask_set_cpu(cpus[i], gic->cpu_hint);
+
 		if (!i)
 			snprintf(gic->name, MANA_IRQ_NAME_SZ, "mana_hwc@pci:%s",
 				 pci_name(pdev));
@@ -1269,17 +1269,18 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
 		irq = pci_irq_vector(pdev, i);
 		if (irq < 0) {
 			err = irq;
-			goto free_mask;
+			free_cpumask_var(gic->cpu_hint);
+			goto free_irq;
 		}
 
 		err = request_irq(irq, mana_gd_intr, 0, gic->name, gic);
-		if (err)
-			goto free_mask;
-		irq_set_affinity_and_hint(irq, req_mask);
-		cpumask_clear(req_mask);
+		if (err) {
+			free_cpumask_var(gic->cpu_hint);
+			goto free_irq;
+		}
+
+		irq_set_affinity_and_hint(irq, gic->cpu_hint);
 	}
-	free_cpumask_var(req_mask);
-	kfree(cpus);
 
 	err = mana_gd_alloc_res_map(nvec, &gc->msix_resource);
 	if (err)
@@ -1288,20 +1289,22 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
 	gc->max_num_msix = nvec;
 	gc->num_msix_usable = nvec;
 
+	kfree(cpus);
 	return 0;
 
-free_mask:
-	free_cpumask_var(req_mask);
-	kfree(cpus);
 free_irq:
 	for (j = i - 1; j >= 0; j--) {
 		irq = pci_irq_vector(pdev, j);
 		gic = &gc->irq_contexts[j];
 
 		irq_update_affinity_hint(irq, NULL);
+		free_cpumask_var(gic->cpu_hint);
 		free_irq(irq, gic);
 	}
 
+	kfree(cpus);
+
+free_gic:
 	kfree(gc->irq_contexts);
 	gc->irq_contexts = NULL;
 free_irq_vector:
@@ -1329,6 +1332,7 @@ static void mana_gd_remove_irqs(struct pci_dev *pdev)
 
 		/* Need to clear the hint before free_irq */
 		irq_update_affinity_hint(irq, NULL);
+		free_cpumask_var(gic->cpu_hint);
 		free_irq(irq, gic);
 	}
 
diff --git a/include/net/mana/gdma.h b/include/net/mana/gdma.h
index 56189e4252da..4dcafecbd89e 100644
--- a/include/net/mana/gdma.h
+++ b/include/net/mana/gdma.h
@@ -342,6 +342,7 @@ struct gdma_irq_context {
 	void (*handler)(void *arg);
 	void *arg;
 	char name[MANA_IRQ_NAME_SZ];
+	cpumask_var_t cpu_hint;
 };
 
 struct gdma_context {
-- 
2.25.1

From: LKML haiyangz <lkmlhyz@microsoft.com> On Behalf Of Haiyang Zhang Sent: Thursday, January 26, 2023 1:05 PM
> 
> After calling irq_set_affinity_and_hint(), the cpumask pointer is
> saved in desc->affinity_hint, and will be used later when reading
> /proc/irq/<num>/affinity_hint. So the cpumask variable needs to be
> allocated per irq, and available until freeing the irq. Otherwise,
> we are accessing freed memory when reading the affinity_hint file.
> 
> To fix the bug, allocate the cpumask per irq, and free it just
> before freeing the irq.

Since the cpumask being passed to irq_set_affinity_and_hint()
always contains exactly one CPU, the code can be considerably
simplified by using the pre-calculated and persistent masks
available as cpumask_of(cpu).  All allocation of cpumasks in this
code goes away, and you can set the affinity_hint to NULL in the
cleanup and remove paths without having to free any masks.

Michael

> 
> Cc: stable@vger.kernel.org
> Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA nodes")
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
>  .../net/ethernet/microsoft/mana/gdma_main.c   | 40 ++++++++++---------
>  include/net/mana/gdma.h                       |  1 +
>  2 files changed, 23 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> index 3bae9d4c1f08..37473ae3859c 100644
> --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> @@ -1219,7 +1219,6 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  	struct gdma_irq_context *gic;
>  	unsigned int max_irqs;
>  	u16 *cpus;
> -	cpumask_var_t req_mask;
>  	int nvec, irq;
>  	int err, i = 0, j;
> 
> @@ -1240,25 +1239,26 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  		goto free_irq_vector;
>  	}
> 
> -	if (!zalloc_cpumask_var(&req_mask, GFP_KERNEL)) {
> -		err = -ENOMEM;
> -		goto free_irq;
> -	}
> -
>  	cpus = kcalloc(nvec, sizeof(*cpus), GFP_KERNEL);
>  	if (!cpus) {
>  		err = -ENOMEM;
> -		goto free_mask;
> +		goto free_gic;
>  	}
>  	for (i = 0; i < nvec; i++)
>  		cpus[i] = cpumask_local_spread(i, gc->numa_node);
> 
>  	for (i = 0; i < nvec; i++) {
> -		cpumask_set_cpu(cpus[i], req_mask);
>  		gic = &gc->irq_contexts[i];
>  		gic->handler = NULL;
>  		gic->arg = NULL;
> 
> +		if (!zalloc_cpumask_var(&gic->cpu_hint, GFP_KERNEL)) {
> +			err = -ENOMEM;
> +			goto free_irq;
> +		}
> +
> +		cpumask_set_cpu(cpus[i], gic->cpu_hint);
> +
>  		if (!i)
>  			snprintf(gic->name, MANA_IRQ_NAME_SZ,
> "mana_hwc@pci:%s",
>  				 pci_name(pdev));
> @@ -1269,17 +1269,18 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  		irq = pci_irq_vector(pdev, i);
>  		if (irq < 0) {
>  			err = irq;
> -			goto free_mask;
> +			free_cpumask_var(gic->cpu_hint);
> +			goto free_irq;
>  		}
> 
>  		err = request_irq(irq, mana_gd_intr, 0, gic->name, gic);
> -		if (err)
> -			goto free_mask;
> -		irq_set_affinity_and_hint(irq, req_mask);
> -		cpumask_clear(req_mask);
> +		if (err) {
> +			free_cpumask_var(gic->cpu_hint);
> +			goto free_irq;
> +		}
> +
> +		irq_set_affinity_and_hint(irq, gic->cpu_hint);
>  	}
> -	free_cpumask_var(req_mask);
> -	kfree(cpus);
> 
>  	err = mana_gd_alloc_res_map(nvec, &gc->msix_resource);
>  	if (err)
> @@ -1288,20 +1289,22 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  	gc->max_num_msix = nvec;
>  	gc->num_msix_usable = nvec;
> 
> +	kfree(cpus);
>  	return 0;
> 
> -free_mask:
> -	free_cpumask_var(req_mask);
> -	kfree(cpus);
>  free_irq:
>  	for (j = i - 1; j >= 0; j--) {
>  		irq = pci_irq_vector(pdev, j);
>  		gic = &gc->irq_contexts[j];
> 
>  		irq_update_affinity_hint(irq, NULL);
> +		free_cpumask_var(gic->cpu_hint);
>  		free_irq(irq, gic);
>  	}
> 
> +	kfree(cpus);
> +
> +free_gic:
>  	kfree(gc->irq_contexts);
>  	gc->irq_contexts = NULL;
>  free_irq_vector:
> @@ -1329,6 +1332,7 @@ static void mana_gd_remove_irqs(struct pci_dev *pdev)
> 
>  		/* Need to clear the hint before free_irq */
>  		irq_update_affinity_hint(irq, NULL);
> +		free_cpumask_var(gic->cpu_hint);
>  		free_irq(irq, gic);
>  	}
> 
> diff --git a/include/net/mana/gdma.h b/include/net/mana/gdma.h
> index 56189e4252da..4dcafecbd89e 100644
> --- a/include/net/mana/gdma.h
> +++ b/include/net/mana/gdma.h
> @@ -342,6 +342,7 @@ struct gdma_irq_context {
>  	void (*handler)(void *arg);
>  	void *arg;
>  	char name[MANA_IRQ_NAME_SZ];
> +	cpumask_var_t cpu_hint;
>  };
> 
>  struct gdma_context {
> --
> 2.25.1

> -----Original Message-----
> From: Michael Kelley (LINUX) <mikelley@microsoft.com>
> Sent: Sunday, January 29, 2023 9:27 AM
> To: Haiyang Zhang <haiyangz@microsoft.com>; linux-hyperv@vger.kernel.org;
> netdev@vger.kernel.org
> Cc: Haiyang Zhang <haiyangz@microsoft.com>; Dexuan Cui
> <decui@microsoft.com>; KY Srinivasan <kys@microsoft.com>; Paul Rosswurm
> <paulros@microsoft.com>; olaf@aepfle.de; vkuznets@redhat.com;
> davem@davemloft.net; linux-kernel@vger.kernel.org; stable@vger.kernel.org
> Subject: RE: [PATCH net, 2/2] net: mana: Fix accessing freed irq affinity_hint
> 
> From: LKML haiyangz <lkmlhyz@microsoft.com> On Behalf Of Haiyang Zhang
> Sent: Thursday, January 26, 2023 1:05 PM
> >
> > After calling irq_set_affinity_and_hint(), the cpumask pointer is
> > saved in desc->affinity_hint, and will be used later when reading
> > /proc/irq/<num>/affinity_hint. So the cpumask variable needs to be
> > allocated per irq, and available until freeing the irq. Otherwise,
> > we are accessing freed memory when reading the affinity_hint file.
> >
> > To fix the bug, allocate the cpumask per irq, and free it just
> > before freeing the irq.
> 
> Since the cpumask being passed to irq_set_affinity_and_hint()
> always contains exactly one CPU, the code can be considerably
> simplified by using the pre-calculated and persistent masks
> available as cpumask_of(cpu).  All allocation of cpumasks in this
> code goes away, and you can set the affinity_hint to NULL in the
> cleanup and remove paths without having to free any masks.
> 
Great idea!
Will update the patch accordingly.

- Haiyang

> -----Original Message-----
> From: Haiyang Zhang <haiyangz@microsoft.com>
> Sent: Sunday, January 29, 2023 1:51 PM
> To: Michael Kelley (LINUX) <mikelley@microsoft.com>; linux-
> hyperv@vger.kernel.org; netdev@vger.kernel.org
> Cc: Dexuan Cui <decui@microsoft.com>; KY Srinivasan <kys@microsoft.com>;
> Paul Rosswurm <paulros@microsoft.com>; olaf@aepfle.de;
> vkuznets@redhat.com; davem@davemloft.net; linux-kernel@vger.kernel.org;
> stable@vger.kernel.org
> Subject: RE: [PATCH net, 2/2] net: mana: Fix accessing freed irq affinity_hint
> 
> 
> 
> > -----Original Message-----
> > From: Michael Kelley (LINUX) <mikelley@microsoft.com>
> > Sent: Sunday, January 29, 2023 9:27 AM
> > To: Haiyang Zhang <haiyangz@microsoft.com>; linux-
> hyperv@vger.kernel.org;
> > netdev@vger.kernel.org
> > Cc: Haiyang Zhang <haiyangz@microsoft.com>; Dexuan Cui
> > <decui@microsoft.com>; KY Srinivasan <kys@microsoft.com>; Paul
> Rosswurm
> > <paulros@microsoft.com>; olaf@aepfle.de; vkuznets@redhat.com;
> > davem@davemloft.net; linux-kernel@vger.kernel.org;
> stable@vger.kernel.org
> > Subject: RE: [PATCH net, 2/2] net: mana: Fix accessing freed irq affinity_hint
> >
> > From: LKML haiyangz <lkmlhyz@microsoft.com> On Behalf Of Haiyang
> Zhang
> > Sent: Thursday, January 26, 2023 1:05 PM
> > >
> > > After calling irq_set_affinity_and_hint(), the cpumask pointer is
> > > saved in desc->affinity_hint, and will be used later when reading
> > > /proc/irq/<num>/affinity_hint. So the cpumask variable needs to be
> > > allocated per irq, and available until freeing the irq. Otherwise,
> > > we are accessing freed memory when reading the affinity_hint file.
> > >
> > > To fix the bug, allocate the cpumask per irq, and free it just
> > > before freeing the irq.
> >
> > Since the cpumask being passed to irq_set_affinity_and_hint()
> > always contains exactly one CPU, the code can be considerably
> > simplified by using the pre-calculated and persistent masks
> > available as cpumask_of(cpu).  All allocation of cpumasks in this
> > code goes away, and you can set the affinity_hint to NULL in the
> > cleanup and remove paths without having to free any masks.
> >
> Great idea!
> Will update the patch accordingly.

Also, I saw this alloc isn't necessary either:
	cpus = kcalloc(nvec, sizeof(*cpus), GFP_KERNEL);

We can simply use the return from cpumask_local_spread()
without saving all cpu numbers in a tmp array.

I will clean this up too :)

Thanks,
- Haiyang

On Thu, Jan 26, 2023 at 01:04:45PM -0800, Haiyang Zhang wrote:
> After calling irq_set_affinity_and_hint(), the cpumask pointer is
> saved in desc->affinity_hint, and will be used later when reading
> /proc/irq/<num>/affinity_hint. So the cpumask variable needs to be
> allocated per irq, and available until freeing the irq. Otherwise,
> we are accessing freed memory when reading the affinity_hint file.
> 
> To fix the bug, allocate the cpumask per irq, and free it just
> before freeing the irq.
> 
> Cc: stable@vger.kernel.org
> Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA nodes")
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
>  .../net/ethernet/microsoft/mana/gdma_main.c   | 40 ++++++++++---------
>  include/net/mana/gdma.h                       |  1 +
>  2 files changed, 23 insertions(+), 18 deletions(-)
> 

Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>