From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f54.google.com (mail-wm1-f54.google.com [209.85.128.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A8AE1C5D5E for ; Mon, 25 May 2026 22:04:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779746691; cv=none; b=LGUVfN2JmBfCCBc5ZzuFQy0i7NlwngNLZ2+lk/wUrE5Lk03JppmLGBkv3CyLTui5kPuh81KpzbGzoim52oxVi77Nx4Spqfp9mvcxkYuD1c4+9JMDtHeKEEBBZxCj4iM+14YgsHFMJ9zcVRGX7BCTSvWrw8cbQfMpSP7XKnkkZtI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779746691; c=relaxed/simple; bh=n7UWqtzQfSDd8ke2zpsyNz1xMduyOx0o5jQ/AXwR+Uo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Fapu2A3w2/x9ibx/M7Cg8tRGjIhzULxQe88tBRdVLQCfHokPrJBZKkC6cdR7r1SV9WWeDZ1bQK6VZ+IIUt8/fH+5s5vpYjYTn+1tylQ2Tq+4YmGVgcC35TKsc7GCJnqIBql2BSKy4cqyurmqL0pe8wZpY903HedG09ubpSTtoEs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=bWipLrsv; arc=none smtp.client-ip=209.85.128.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="bWipLrsv" Received: by mail-wm1-f54.google.com with SMTP id 5b1f17b1804b1-49068493267so9400065e9.1 for ; Mon, 25 May 2026 15:04:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779746688; x=1780351488; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=7RTCGCGe4Su+57ooJAGzTmDyHCOTy856CxFupslfh74=; b=bWipLrsv5cnAe/5CxBnqkmhH/zaUiiitF3vX99KLGSiaIoMQvfaJoTUUTBwVV0esrT OcYHmWrAr5+tRvfh+F/SP/+A+IoH4QUICezkKUb37Rarl5FciRRDDGNAA/MjKAoT5/uv SFw0AgQO4qqcxEP0HwXxMi31u/ajm5lyVrVJbKmGZ1MtO8xOrWDLSlkbrJoPhYA7qPUV IXrT7J/ibBPh0V8hwEwnWBoUH0Tf0iF4KYffP1CTU2ENpjX41zfyV9TdDctvCJpxcCFw BKAw1nGfEN3dPdnt1SFoJjmxnRFxGcAV0NOeQ04MXDp0HjgvRDuqCUN12AxiYi0k6wiM Dn5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779746688; x=1780351488; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=7RTCGCGe4Su+57ooJAGzTmDyHCOTy856CxFupslfh74=; b=GVMRR7KGD/Yfib1NswaryQzbJ8o5bIXsHVatiTiJCjUcQe37ukecseD4L8mTBoElzM Oxn8Zfk3Cd4r/xZ6w2baCFk23g8hE8RuAKmTNOlrbKrFjZVLqqjpj3SJ5qpU1D56V6bG WrtDkKP6SKG0Be7f2xu9zSKLn46hs2ndYV6sVlsc4SX0zwRbnzfeGyEM8hX3v6yi3F8L gD0ElzzDYvFFDL+YNYQmGXjW1G1hnz0gn28C8MhHj8nst/mTraVCggQI4t4W5nUAyDWM O+ZCKxtka8eqMmMV87Y3Lhr6hNK5jhqhLdUtSG0CmKtNosy2sQr2w5nA66ztR1xhup9j vM8A== X-Forwarded-Encrypted: i=1; AFNElJ9HQQKBBlYsFCiebYMIZhC3auxhtHTxC6fgsDoCNddqJmL/kXJLRwzyXPtHeAQ4NvlLk0WND4o=@vger.kernel.org X-Gm-Message-State: AOJu0Yyxlpj8TGc4UOK0RWVQFJDI+PhIOZe4g0LOoistybZGt0PvjPIv pl5fIP6ski97NCBcedATAdv1Pbc5lEBlmPm8CUJUVGnUwbK1A+OD/2kA X-Gm-Gg: Acq92OHBxaSrp0yQ80kN1WL38we/TQ5jOLI/hGe+dtZW6ZiG/ZS7QWTGUERGwcDmIEi P/dOIh13AXNzV7EbqEf5u/LdK/czwidg4Gei5x1LGc/i4MD/lTUMu4QuqldNdvs/CY5B4Dkg7iw A+IHzgGrKzuLGbiX8WUM80fSR4fAyuNiFLnq1QTblvv9nTEcxw9Pc15On6Ci3FSKL78BR3AozUh xqPVmr1/K2PbbmQyuu2TA/ZWm8QEHkDtBME5P7jT4kZTwTXxTulrRudTelwik8lRXXBt1uz+roK VzHXrwQX/9cy+0t4n7SmI1QkQe24jgzK9qdTqx1ZumB3jswdNGgEaHVtZnkFNdeWriIp2/yTH6m D/kyYxWCnzgyLpvyfTK+zxqw5Gbnx9gcfFwy0hfe88gxIttXZJdAfxVYhgmTsGqLHVkX2VUd4Tu aup8L8TVLP02p4zE7cxcDdo61zb6l06l4= X-Received: by 2002:a05:600d:4453:20b0:490:2238:4021 with SMTP id 5b1f17b1804b1-49042494fe3mr189225585e9.8.1779746688062; Mon, 25 May 2026 15:04:48 -0700 (PDT) Received: from x1.tail0e71db.ts.net ([46.140.7.198]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49048f70f55sm80501465e9.17.2026.05.25.15.04.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2026 15:04:47 -0700 (PDT) From: Ruslan Valiyev To: John Johansen Cc: Paul Moore , James Morris , "Serge E . Hallyn" , Georgia Garcia , Cengiz Can , Colin Ian King , apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH] apparmor: fix use-after-free in rawdata dedup loop Date: Tue, 26 May 2026 00:04:46 +0200 Message-ID: <20260525220446.975352-1-linuxoid@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- security/apparmor/include/policy_unpack.h | 19 +++++++++++++++++++ security/apparmor/policy.c | 8 ++++++-- 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/security/apparmor/include/policy_unpack.h b/security/apparmor/include/policy_unpack.h index e5a95dc4da1f..b9de0fdf9ee5 100644 --- a/security/apparmor/include/policy_unpack.h +++ b/security/apparmor/include/policy_unpack.h @@ -163,6 +163,25 @@ aa_get_profile_loaddata(struct aa_loaddata *data) 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); diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c index b6a5eb4021db..e103cce6f4af 100644 --- a/security/apparmor/policy.c +++ b/security/apparmor/policy.c @@ -1223,8 +1223,12 @@ ssize_t aa_replace_profiles(struct aa_ns *policy_ns, struct aa_label *label, 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; base-commit: e7ae89a0c97ce2b68b0983cd01eda67cf373517d -- 2.43.0