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[96.51.42.105]) by smtp.googlemail.com with ESMTPSA id 98e67ed59e1d1-392e586977esm4878a91.3.2026.08.10.16.56.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Aug 2026 16:56:30 -0700 (PDT) Message-ID: Date: Mon, 10 Aug 2026 16:56:28 -0700 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] apparmor: fix out-of-bounds write when null terminating a label vec To: Hyunwoo Kim , georgia.garcia@canonical.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, maxime.belair@canonical.com, cengiz.can@canonical.com Cc: apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org References: Content-Language: en-US From: John Johansen Autocrypt: addr=john.johansen@canonical.com; keydata= xsFNBE5mrPoBEADAk19PsgVgBKkImmR2isPQ6o7KJhTTKjJdwVbkWSnNn+o6Up5knKP1f49E BQlceWg1yp/NwbR8ad+eSEO/uma/K+PqWvBptKC9SWD97FG4uB4/caomLEU97sLQMtnvGWdx rxVRGM4anzWYMgzz5TZmIiVTZ43Ou5VpaS1Vz1ZSxP3h/xKNZr/TcW5WQai8u3PWVnbkjhSZ PHv1BghN69qxEPomrJBm1gmtx3ZiVmFXluwTmTgJOkpFol7nbJ0ilnYHrA7SX3CtR1upeUpM a/WIanVO96WdTjHHIa43fbhmQube4txS3FcQLOJVqQsx6lE9B7qAppm9hQ10qPWwdfPy/+0W 6AWtNu5ASiGVCInWzl2HBqYd/Zll93zUq+NIoCn8sDAM9iH+wtaGDcJywIGIn+edKNtK72AM gChTg/j1ZoWH6ZeWPjuUfubVzZto1FMoGJ/SF4MmdQG1iQNtf4sFZbEgXuy9cGi2bomF0zvy BJSANpxlKNBDYKzN6Kz09HUAkjlFMNgomL/cjqgABtAx59L+dVIZfaF281pIcUZzwvh5+JoG eOW5uBSMbE7L38nszooykIJ5XrAchkJxNfz7k+FnQeKEkNzEd2LWc3QF4BQZYRT6PHHga3Rg ykW5+1wTMqJILdmtaPbXrF3FvnV0LRPcv4xKx7B3fGm7ygdoowARAQABzStKb2huIEpvaGFu c2VuIDxqb2huLmpvaGFuc2VuQGNhbm9uaWNhbC5jb20+wsF3BBMBCgAhBQJOjRdaAhsDBQsJ CAcDBRUKCQgLBRYCAwEAAh4BAheAAAoJEAUvNnAY1cPYi0wP/2PJtzzt0zi4AeTrI0w3Rj8E Waa1NZWw4GGo6ehviLfwGsM7YLWFAI8JB7gsuzX/im16i9C3wHYXKs9WPCDuNlMc0rvivqUI JXHHfK7UHtT0+jhVORyyVVvX+qZa7HxdZw3jK+ROqUv4bGnImf31ll99clzo6HpOY59soa8y 66/lqtIgDckcUt/1ou9m0DWKwlSvulL1qmD25NQZSnvB9XRZPpPd4bea1RTa6nklXjznQvTm MdLq5aJ79j7J8k5uLKvE3/pmpbkaieEsGr+azNxXm8FPcENV7dG8Xpd0z06E+fX5jzXHnj69 DXXc3yIvAXsYZrXhnIhUA1kPQjQeNG9raT9GohFPMrK48fmmSVwodU8QUyY7MxP4U6jE2O9L 7v7AbYowNgSYc+vU8kFlJl4fMrX219qU8ymkXGL6zJgtqA3SYHskdDBjtytS44OHJyrrRhXP W1oTKC7di/bb8jUQIYe8ocbrBz3SjjcL96UcQJecSHu0qmUNykgL44KYzEoeFHjr5dxm+DDg OBvtxrzd5BHcIbz0u9ClbYssoQQEOPuFmGQtuSQ9FmbfDwljjhrDxW2DFZ2dIQwIvEsg42Hq 5nv/8NhW1whowliR5tpm0Z0KnQiBRlvbj9V29kJhs7rYeT/dWjWdfAdQSzfoP+/VtPRFkWLr 0uCwJw5zHiBgzsFNBE5mrPoBEACirDqSQGFbIzV++BqYBWN5nqcoR+dFZuQL3gvUSwku6ndZ vZfQAE04dKRtIPikC4La0oX8QYG3kI/tB1UpEZxDMB3pvZzUh3L1EvDrDiCL6ef93U+bWSRi GRKLnNZoiDSblFBST4SXzOR/m1wT/U3Rnk4rYmGPAW7ltfRrSXhwUZZVARyJUwMpG3EyMS2T dLEVqWbpl1DamnbzbZyWerjNn2Za7V3bBrGLP5vkhrjB4NhrufjVRFwERRskCCeJwmQm0JPD IjEhbYqdXI6uO+RDMgG9o/QV0/a+9mg8x2UIjM6UiQ8uDETQha55Nd4EmE2zTWlvxsuqZMgy W7gu8EQsD+96JqOPmzzLnjYf9oex8F/gxBSEfE78FlXuHTopJR8hpjs6ACAq4Y0HdSJohRLn 5r2CcQ5AsPEpHL9rtDW/1L42/H7uPyIfeORAmHFPpkGFkZHHSCQfdP4XSc0Obk1olSxqzCAm uoVmRQZ3YyubWqcrBeIC3xIhwQ12rfdHQoopELzReDCPwmffS9ctIb407UYfRQxwDEzDL+m+ TotTkkaNlHvcnlQtWEfgwtsOCAPeY9qIbz5+i1OslQ+qqGD2HJQQ+lgbuyq3vhefv34IRlyM sfPKXq8AUTZbSTGUu1C1RlQc7fpp8W/yoak7dmo++MFS5q1cXq29RALB/cfpcwARAQABwsFf BBgBCgAJBQJOZqz6AhsMAAoJEAUvNnAY1cPYP9cP/R10z/hqLVv5OXWPOcpqNfeQb4x4Rh4j h/jS9yjes4uudEYU5xvLJ9UXr0wp6mJ7g7CgjWNxNTQAN5ydtacM0emvRJzPEEyujduesuGy a+O6dNgi+ywFm0HhpUmO4sgs9SWeEWprt9tWrRlCNuJX+u3aMEQ12b2lslnoaOelghwBs8IJ r998vj9JBFJgdeiEaKJLjLmMFOYrmW197As7DTZ+R7Ef4gkWusYFcNKDqfZKDGef740Xfh9d yb2mJrDeYqwgKb7SF02Hhp8ZnohZXw8ba16ihUOnh1iKH77Ff9dLzMEJzU73DifOU/aArOWp JZuGJamJ9EkEVrha0B4lN1dh3fuP8EjhFZaGfLDtoA80aPffK0Yc1R/pGjb+O2Pi0XXL9AVe qMkb/AaOl21F9u1SOosciy98800mr/3nynvid0AKJ2VZIfOP46nboqlsWebA07SmyJSyeG8c XA87+8BuXdGxHn7RGj6G+zZwSZC6/2v9sOUJ+nOna3dwr6uHFSqKw7HwNl/PUGeRqgJEVu++ +T7sv9+iY+e0Y+SolyJgTxMYeRnDWE6S77g6gzYYHmcQOWP7ZMX+MtD4SKlf0+Q8li/F9GUL p0rw8op9f0p1+YAhyAd+dXWNKf7zIfZ2ME+0qKpbQnr1oizLHuJX/Telo8KMmHter28DPJ03 lT9Q Organization: Canonical In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/10/26 02:51, Hyunwoo Kim wrote: > aa_vec_unique() null terminates at vec[n - dups] when VEC_FLAG_TERMINATE > is passed. If the components are all distinct no duplicates are dropped, > dups is 0 and the terminator goes to vec[n], so the caller has to provide > room for n + 1 entries. > > aa_label_strn_parse() sets up its vector with vec_setup(profile, vec, len, > gfp) and then calls aa_vec_unique(vec, len, VEC_FLAG_TERMINATE), but > vec_setup() does not reserve the terminator entry. Up to LOCAL_VEC_ENTRIES > it uses the local array of LOCAL_VEC_ENTRIES pointers, above that it > allocates exactly len pointers. The terminator therefore lands one entry > past the end of the local array when len is LOCAL_VEC_ENTRIES, and one > entry past the end of the allocation when len is larger. > > len comes from the number of "//&" separated components in the label name > and label_count_strn_entries() does not bound it. An unprivileged task > reaches the parse by writing to /proc/self/attr/apparmor/current or through > lsm_set_self_attr(2), both of which go through do_setattr(), and the name > is parsed before the change_profile permission is checked. > The query_label() path behind the securityfs .access file, which is > mode 0666, performs no permission check at all. Every component has to > resolve to a loaded profile, so a system with policy loaded is required. > > The other two VEC_FLAG_TERMINATE users work on a label vec that > aa_label_alloc() has already sized with "+ 1 for null terminator entry on > vec". Reserve the same entry in vec_setup() and DEFINE_VEC(). Passing > len + 1 from the caller instead would move len == LOCAL_VEC_ENTRIES out of > the local array and into kzalloc(). > > Fixes: f1bd904175e8 ("apparmor: add the base fns() for domain labels") > Cc: stable@vger.kernel.org > Signed-off-by: Hyunwoo Kim Acked-by: John Johansen I have pulled this into my tree > --- > security/apparmor/include/label.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/security/apparmor/include/label.h b/security/apparmor/include/label.h > index b5a722a47fd2c8..37cb135de32320 100644 > --- a/security/apparmor/include/label.h > +++ b/security/apparmor/include/label.h > @@ -23,7 +23,7 @@ struct aa_ruleset; > > #define LOCAL_VEC_ENTRIES 8 > #define DEFINE_VEC(T, V) \ > - struct aa_ ## T *(_ ## V ## _localtmp)[LOCAL_VEC_ENTRIES]; \ > + struct aa_ ## T *(_ ## V ## _localtmp)[LOCAL_VEC_ENTRIES + 1]; \ > struct aa_ ## T **(V) > > #define vec_setup(T, V, N, GFP) \ > @@ -31,10 +31,10 @@ struct aa_ruleset; > if ((N) <= LOCAL_VEC_ENTRIES) { \ > typeof(N) i; \ > (V) = (_ ## V ## _localtmp); \ > - for (i = 0; i < (N); i++) \ > + for (i = 0; i <= (N); i++) \ > (V)[i] = NULL; \ > } else \ > - (V) = kzalloc(sizeof(struct aa_ ## T *) * (N), (GFP)); \ > + (V) = kzalloc_objs(struct aa_ ## T *, (N) + 1, (GFP)); \ > (V) ? 0 : -ENOMEM; \ > }) >