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[95.119.217.226]) by smtp.gmail.com with ESMTPSA id kq15-20020a170906abcf00b00a462520d561sm1888870ejb.54.2024.03.15.10.29.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Mar 2024 10:29:05 -0700 (PDT) From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= To: selinux@vger.kernel.org Cc: Paul Moore , Stephen Smalley , Ondrej Mosnacek , linux-kernel@vger.kernel.org Subject: [PATCH v2] selinux: reject invalid ebitmaps Date: Fri, 15 Mar 2024 18:28:44 +0100 Message-ID: <20240315172859.634263-1-cgzones@googlemail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Reject ebitmaps with a node containing an empty map or with an incorrect highbit. Both checks are already performed by userspace, the former since 2008 (patch 13cd4c896068 ("initial import from svn trunk revision 2950")), the latter since v2.7 in 2017 (patch 75b14a5de10a ("libsepol: ebitmap: reject loading bitmaps with incorrect high bit")). Signed-off-by: Christian G=C3=B6ttsche --- v2: update wording as suggested in [1] [1]: https://lore.kernel.org/selinux/d476b21729cafb28c1b881113a563b1f.paul@= paul-moore.com/ --- security/selinux/ss/ebitmap.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c index 67c1a73cd5ee..f1ba333f127d 100644 --- a/security/selinux/ss/ebitmap.c +++ b/security/selinux/ss/ebitmap.c @@ -448,6 +448,10 @@ int ebitmap_read(struct ebitmap *e, void *fp) goto bad; } map =3D le64_to_cpu(mapbits); + if (!map) { + pr_err("SELinux: ebitmap: empty map\n"); + goto bad; + } =20 index =3D (startbit - n->startbit) / EBITMAP_UNIT_SIZE; while (map) { @@ -455,6 +459,13 @@ int ebitmap_read(struct ebitmap *e, void *fp) map =3D EBITMAP_SHIFT_UNIT_SIZE(map); } } + + if (n && n->startbit + EBITMAP_SIZE !=3D e->highbit) { + pr_err("SELinux: ebitmap: high bit %d is not equal to the expected value= %ld\n", + e->highbit, n->startbit + EBITMAP_SIZE); + goto bad; + } + ok: rc =3D 0; out: --=20 2.43.0