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Subject[PATCH net-next 01/14] lib: cpu_rmap: Avoid use after free on rmap->obj array entries
Date
From: Eli Cohen <elic@nvidia.com>

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().

Fixes: c39649c331c7 ("lib: cpu_rmap: CPU affinity reverse-mapping")
CC: Ben Hutchings <bhutchings@solarflare.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: David Decotigny <decot@googlers.com>
CC: Eric Dumazet <edumazet@google.com>
CC: linux-kernel@vger.kernel.org
Signed-off-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
---
lib/cpu_rmap.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
index f08d9c56f712..e77f12bb3c77 100644
--- a/lib/cpu_rmap.c
+++ b/lib/cpu_rmap.c
@@ -232,7 +232,8 @@ void free_irq_cpu_rmap(struct cpu_rmap *rmap)

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

cpu_rmap_put(rmap);
@@ -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;
--
2.39.1
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