From 83c8ab8503adf56bf68dafc7a382f4946c87da79 Mon Sep 17 00:00:00 2001 From: Ondrej Mosnacek Date: Fri, 19 Nov 2021 14:45:20 +0100 Subject: selinux: fix NULL-pointer dereference when hashtab allocation fails 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@vger.kernel.org Fixes: 03414a49ad5f ("selinux: do not allocate hashtabs dynamically") Signed-off-by: Ondrej Mosnacek Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman --- security/selinux/ss/hashtab.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) (limited to 'security') diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c index b8f6b3e0a921..a91fb0ed00de 100644 --- 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, -- cgit v1.2.3