From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 70AA730EF95; Thu, 2 Jul 2026 16:54:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783011266; cv=none; b=UoU/aJmaiO8Sssd5EC+lJOqBTfFUDbCtytgZaEfmLe4WP+olh73MDVIZ6ApSIE1NE55TbVGiL9bFUnjlmR0Wi+7StBAuaOYISoATbtjt1ykcOwn3onbM42D8yYbYpLcud8EAHc1dvXk4OGDsJcqfqozJmn8vpgjpIFGaJVda50c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783011266; c=relaxed/simple; bh=O6gttGzlXm9EWp60Ife9oQ25a/bwHWa/qWAshxaxtAE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=A+iOann2fX3Bc6qWCQAt9CoDJMGbSIi+X8i5yGmE/hjOyQibC07QvUU3kwyTpJ3lx2uQ+GvFYBoqj0D+tJpsVT3AjT2bgY+yxqrjnZAR9Z9hIq/BfwcucgD4kBdB/g6l95W+HRqvAIvuLIpbQ27/FMgtS79RvkddndZR7Maryc8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cBmPyXIh; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cBmPyXIh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7A8E1F000E9; Thu, 2 Jul 2026 16:54:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783011265; bh=6dIFafrt7b1KWDSABPPaxDQR0m5ePtO+2fl/zfRGKJM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=cBmPyXIhg/7glQvo0nSDlsxd+SGZaVGckG6lN26Ogfw4Ja6bzIz1LWhscZZSPyjrY NW1IASeuvDA6jSMk3OfxjOy5EGzL24du7Fv+2z3nWoFvxqdQNzkBjy9iff2hrSHHpr aM8iFyNCCRKvtKJyckQHF6gqYin6+ywkWhTVS2K0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Colin Ian King , Ruslan Valiyev , John Johansen Subject: [PATCH 6.18 041/108] apparmor: fix use-after-free in rawdata dedup loop Date: Thu, 2 Jul 2026 18:20:38 +0200 Message-ID: <20260702155112.960493438@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155112.110058792@linuxfoundation.org> References: <20260702155112.110058792@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ruslan Valiyev commit 6f060496d03e4dc560a40f73770bd08335cb7a27 upstream. aa_replace_profiles() walks ns->rawdata_list to dedup the incoming policy blob against entries already attached to existing profiles. Per the kernel-doc on struct aa_loaddata, list membership does not hold a reference: profiles hold pcount, and when the last pcount drops, do_ploaddata_rmfs() is queued on a workqueue that takes ns->lock and removes the entry. Between dropping the last pcount and the workqueue running, an entry remains on the list with pcount == 0. aa_get_profile_loaddata() is an unconditional kref_get() on pcount, so when the dedup loop hits such an entry, refcount hardening reports refcount_t: addition on 0; use-after-free. inside aa_replace_profiles(), and the poisoned counter then trips "saturated" and "underflow" warnings on the subsequent uses of the same loaddata. Before commit a0b7091c4de4 ("apparmor: fix race on rawdata dereference") the dedup path used a get_unless_zero-style helper on a single counter, so the existing "if (tmp)" guard was meaningful. The split-refcount refactor introduced aa_get_profile_loaddata(), which has plain kref_get() semantics, and the guard quietly became a no-op. Introduce aa_get_profile_loaddata_not0(), matching the existing _not0 convention used by aa_get_profile_not0(), and use it for the rawdata_list dedup lookup so dying entries are skipped. Reproduced on x86_64 with v7.1-rc5 in QEMU+KVM running Ubuntu 24.04 + stress-ng 0.17.06: stress-ng --apparmor 1 --klog-check --timeout 60s Without this patch the three refcount_t warnings fire within a few seconds. With it the same 60 s run is clean. Coverage is a smoke-test only; a longer soak with CONFIG_KASAN, CONFIG_KCSAN and CONFIG_PROVE_LOCKING would be welcome from anyone with the cycles. Fixes: a0b7091c4de4 ("apparmor: fix race on rawdata dereference") Reported-by: Colin Ian King Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221513 Cc: stable@vger.kernel.org Signed-off-by: Ruslan Valiyev Signed-off-by: John Johansen Signed-off-by: Greg Kroah-Hartman --- security/apparmor/include/policy_unpack.h | 19 +++++++++++++++++++ security/apparmor/policy.c | 8 ++++++-- 2 files changed, 25 insertions(+), 2 deletions(-) --- a/security/apparmor/include/policy_unpack.h +++ b/security/apparmor/include/policy_unpack.h @@ -163,6 +163,25 @@ aa_get_profile_loaddata(struct aa_loadda return data; } +/** + * aa_get_profile_loaddata_not0 - get a profile reference count if not zero + * @data: reference to get a count on + * + * Like aa_get_profile_loaddata(), but safe to call on an entry that may + * be on a list (e.g. ns->rawdata_list) where the last pcount has already + * dropped and the deferred cleanup has not yet run. + * + * Returns: pointer to reference, or %NULL if @data is NULL or its + * profile refcount has already reached zero. + */ +static inline struct aa_loaddata * +aa_get_profile_loaddata_not0(struct aa_loaddata *data) +{ + if (data && kref_get_unless_zero(&data->pcount)) + return data; + return NULL; +} + void __aa_loaddata_update(struct aa_loaddata *data, long revision); bool aa_rawdata_eq(struct aa_loaddata *l, struct aa_loaddata *r); void aa_loaddata_kref(struct kref *kref); --- a/security/apparmor/policy.c +++ b/security/apparmor/policy.c @@ -1206,8 +1206,12 @@ ssize_t aa_replace_profiles(struct aa_ns if (aa_rawdata_eq(rawdata_ent, udata)) { struct aa_loaddata *tmp; - tmp = aa_get_profile_loaddata(rawdata_ent); - /* check we didn't fail the race */ + /* + * Entries remain on rawdata_list with + * pcount == 0 until do_ploaddata_rmfs() + * runs; only take a live profile ref. + */ + tmp = aa_get_profile_loaddata_not0(rawdata_ent); if (tmp) { aa_put_profile_loaddata(udata); udata = tmp;