+ mm-kasan-fix-null-pointer-dereference-warning-in-qlink_to_cache.patch added to mm-hotfixes-unstable branch

+ mm-kasan-fix-null-pointer-dereference-warning-in-qlink_to_cache.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/kasan: fix null pointer dereference warning in qlink_to_cache()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-kasan-fix-null-pointer-dereference-warning-in-qlink_to_cache.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-kasan-fix-null-pointer-dereference-warning-in-qlink_to_cache.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Gautam Menghani <gautammenghani201@gmail.com>
Subject: mm/kasan: fix null pointer dereference warning in qlink_to_cache()
Date: Sun, 26 Jun 2022 22:33:55 +0530

virt_to_slab() declared in slab.h can return NULL if the address does not
belong to a slab.  This case is not handled in qlink_to_cache() in
quarantine.c, which can cause a NULL pointer dereference in
"virt_to_slab(qlink)->slab_cache".  This issue was discovered by fanalyzer
(my gcc version: 12.1.1 20220507)

Link: https://lkml.kernel.org/r/20220626170355.198913-1-gautammenghani201@gmail.com
Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kasan/quarantine.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/mm/kasan/quarantine.c~mm-kasan-fix-null-pointer-dereference-warning-in-qlink_to_cache
+++ a/mm/kasan/quarantine.c
@@ -128,7 +128,13 @@ static unsigned long quarantine_batch_si
 
 static struct kmem_cache *qlink_to_cache(struct qlist_node *qlink)
 {
-	return virt_to_slab(qlink)->slab_cache;
+	struct slab *folio_slab = virt_to_slab(qlink);
+
+	if (!folio_slab) {
+		pr_warn("The address %p does not belong to a slab", qlink);
+		return NULL;
+	}
+	return folio_slab->slab_cache;
 }
 
 static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
_

Patches currently in -mm which might be from gautammenghani201@gmail.com are

mm-kasan-fix-null-pointer-dereference-warning-in-qlink_to_cache.patch