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Message-Id: <20211124115707.268031404@linuxfoundation.org>
Date: Wed, 24 Nov 2021 12:59:04 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Ondrej Mosnacek <omosnace@...hat.com>,
Paul Moore <paul@...l-moore.com>
Subject: [PATCH 5.10 148/154] selinux: fix NULL-pointer dereference when hashtab allocation fails
From: Ondrej Mosnacek <omosnace@...hat.com>
commit dc27f3c5d10c58069672215787a96b4fae01818b upstream.
When the hash table slot array allocation fails in hashtab_init(),
h->size is left initialized with a non-zero value, but the h->htable
pointer is NULL. This may then cause a NULL pointer dereference, since
the policydb code relies on the assumption that even after a failed
hashtab_init(), hashtab_map() and hashtab_destroy() can be safely called
on it. Yet, these detect an empty hashtab only by looking at the size.
Fix this by making sure that hashtab_init() always leaves behind a valid
empty hashtab when the allocation fails.
Cc: stable@...r.kernel.org
Fixes: 03414a49ad5f ("selinux: do not allocate hashtabs dynamically")
Signed-off-by: Ondrej Mosnacek <omosnace@...hat.com>
Signed-off-by: Paul Moore <paul@...l-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
security/selinux/ss/hashtab.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
--- a/security/selinux/ss/hashtab.c
+++ b/security/selinux/ss/hashtab.c
@@ -30,13 +30,20 @@ static u32 hashtab_compute_size(u32 nel)
int hashtab_init(struct hashtab *h, u32 nel_hint)
{
- h->size = hashtab_compute_size(nel_hint);
+ u32 size = hashtab_compute_size(nel_hint);
+
+ /* should already be zeroed, but better be safe */
h->nel = 0;
- if (!h->size)
- return 0;
+ h->size = 0;
+ h->htable = NULL;
- h->htable = kcalloc(h->size, sizeof(*h->htable), GFP_KERNEL);
- return h->htable ? 0 : -ENOMEM;
+ if (size) {
+ h->htable = kcalloc(size, sizeof(*h->htable), GFP_KERNEL);
+ if (!h->htable)
+ return -ENOMEM;
+ h->size = size;
+ }
+ return 0;
}
int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
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