LKML Archive on lore.kernel.org
 help / Atom feed
From: Ondrej Mosnacek <omosnace@redhat.com>
To: selinux@vger.kernel.org, Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org,
	Ondrej Mosnacek <omosnace@redhat.com>,
	syzbot+a57b2aff60832666fc28@syzkaller.appspotmail.com
Subject: [PATCH] selinux: fix NULL dereference in policydb_destroy()
Date: Sun, 17 Mar 2019 14:46:53 +0100
Message-ID: <20190317134653.26824-1-omosnace@redhat.com> (raw)

The conversion to kvmalloc() forgot to account for the possibility that
p->type_attr_map_array might be null in policydb_destroy().

Fix this by destroying its contents only if it is not NULL.

Also make sure ebitmap_init() is called on all entries before
policydb_destroy() can be called. Right now this is a no-op, because
both kvcalloc() and ebitmap_init() just zero out the whole struct, but
let's rather not rely on a specific implementation.

Reported-by: syzbot+a57b2aff60832666fc28@syzkaller.appspotmail.com
Fixes: acdf52d97f82 ("selinux: convert to kvmalloc")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
---
 security/selinux/ss/policydb.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

NOTE: This applies directly on top of current Linus' tree, since the
problematic commit is not present in the selinux/stable-5.1 branch.

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 6b576e588725..daecdfb15a9c 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -828,9 +828,11 @@ void policydb_destroy(struct policydb *p)
 	hashtab_map(p->range_tr, range_tr_destroy, NULL);
 	hashtab_destroy(p->range_tr);
 
-	for (i = 0; i < p->p_types.nprim; i++)
-		ebitmap_destroy(&p->type_attr_map_array[i]);
-	kvfree(p->type_attr_map_array);
+	if (p->type_attr_map_array) {
+		for (i = 0; i < p->p_types.nprim; i++)
+			ebitmap_destroy(&p->type_attr_map_array[i]);
+		kvfree(p->type_attr_map_array);
+	}
 
 	ebitmap_destroy(&p->filename_trans_ttypes);
 	ebitmap_destroy(&p->policycaps);
@@ -2496,10 +2498,13 @@ int policydb_read(struct policydb *p, void *fp)
 	if (!p->type_attr_map_array)
 		goto bad;
 
+	/* just in case ebitmap_init() becomes more than just a memset(0): */
+	for (i = 0; i < p->p_types.nprim; i++)
+		ebitmap_init(&p->type_attr_map_array[i]);
+
 	for (i = 0; i < p->p_types.nprim; i++) {
 		struct ebitmap *e = &p->type_attr_map_array[i];
 
-		ebitmap_init(e);
 		if (p->policyvers >= POLICYDB_VERSION_AVTAB) {
 			rc = ebitmap_read(e, fp);
 			if (rc)
-- 
2.20.1


             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-17 13:46 Ondrej Mosnacek [this message]
2019-03-18 13:42 ` Stephen Smalley
2019-03-18 16:29 ` Paul Moore

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190317134653.26824-1-omosnace@redhat.com \
    --to=omosnace@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=kent.overstreet@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=paul@paul-moore.com \
    --cc=sds@tycho.nsa.gov \
    --cc=selinux@vger.kernel.org \
    --cc=syzbot+a57b2aff60832666fc28@syzkaller.appspotmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org linux-kernel@archiver.kernel.org
	public-inbox-index lkml


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox