Commit cc2d2b3d authored Feb 08, 2023 by Eli Cohen Committed by Greg Kroah-Hartman May 30, 2023

lib: cpu_rmap: Avoid use after free on rmap->obj array entries



[ Upstream commit 4e0473f1060aa49621d40a113afde24818101d37 ]

When calling irq_set_affinity_notifier() with NULL at the notify
argument, it will cause freeing of the glue pointer in the
corresponding array entry but will leave the pointer in the array. A
subsequent call to free_irq_cpu_rmap() will try to free this entry again
leading to possible use after free.

Fix that by setting NULL to the array entry and checking that we have
non-zero at the array entry when iterating over the array in
free_irq_cpu_rmap().

The current code does not suffer from this since there are no cases
where irq_set_affinity_notifier(irq, NULL) (note the NULL passed for the
notify arg) is called, followed by a call to free_irq_cpu_rmap() so we
don't hit and issue. Subsequent patches in this series excersize this
flow, hence the required fix.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 89f5055f

lib/cpu_rmap.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -232,6 +232,7 @@ void free_irq_cpu_rmap(struct cpu_rmap *rmap)

		for (index = 0; index < rmap->used; index++) {
		glue = rmap->obj[index];
		if (glue)
		irq_set_affinity_notifier(glue->notify.irq, NULL);
		}

		@@ -268,6 +269,7 @@ static void irq_cpu_rmap_release(struct kref *ref)
		container_of(ref, struct irq_glue, notify.kref);

		cpu_rmap_put(glue->rmap);
		glue->rmap->obj[glue->index] = NULL;
		kfree(glue);
		}

		@@ -297,6 +299,7 @@ int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq)
		rc = irq_set_affinity_notifier(irq, &glue->notify);
		if (rc) {
		cpu_rmap_put(glue->rmap);
		rmap->obj[glue->index] = NULL;
		kfree(glue);
		}
		return rc;