From: Ben Hutchings <ben@decadent.org.uk>
Date: Fri, 2 Jun 2023 18:28:15 +0000 (+0200)
Subject: lib: cpu_rmap: Fix potential use-after-free in irq_cpu_rmap_release()
X-Git-Tag: v4.14.318~13
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=53c1353ad70c74abd4223ab75be7c1fadbb1ac34;p=thirdparty%2Fkernel%2Fstable.git

lib: cpu_rmap: Fix potential use-after-free in irq_cpu_rmap_release()

[ Upstream commit 7c5d4801ecf0564c860033d89726b99723c55146 ]

irq_cpu_rmap_release() calls cpu_rmap_put(), which may free the rmap.
So we need to clear the pointer to our glue structure in rmap before
doing that, not after.

Fixes: 4e0473f1060a ("lib: cpu_rmap: Avoid use after free on rmap->obj array entries")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/ZHo0vwquhOy3FaXc@decadent.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
index f52389054a24f..a0de1b2579f71 100644
--- a/lib/cpu_rmap.c
+++ b/lib/cpu_rmap.c
@@ -271,8 +271,8 @@ static void irq_cpu_rmap_release(struct kref *ref)
 	struct irq_glue *glue =
 		container_of(ref, struct irq_glue, notify.kref);
 
-	cpu_rmap_put(glue->rmap);
 	glue->rmap->obj[glue->index] = NULL;
+	cpu_rmap_put(glue->rmap);
 	kfree(glue);
 }