linux-kernel - [PATCH net-next 01/14] lib: cpu_rmap: Avoid use after free on rmap->obj array entries

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Message-Id: <20230220061442.403092-2-saeed@kernel.org>
Date:   Sun, 19 Feb 2023 22:14:29 -0800
From:   Saeed Mahameed <saeed@...nel.org>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     Saeed Mahameed <saeedm@...dia.com>, netdev@...r.kernel.org,
        Tariq Toukan <tariqt@...dia.com>, Eli Cohen <elic@...dia.com>,
        Ben Hutchings <bhutchings@...arflare.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Decotigny <decot@...glers.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next 01/14] lib: cpu_rmap: Avoid use after free on rmap->obj array entries

From: Eli Cohen <elic@...dia.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@...arflare.com>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: David Decotigny <decot@...glers.com>
CC: Eric Dumazet <edumazet@...gle.com>
CC: linux-kernel@...r.kernel.org
Signed-off-by: Eli Cohen <elic@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.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