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 7294242B317 for ; Thu, 2 Jul 2026 08:34:12 +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=1782981254; cv=none; b=ObRIMrBOXv0n3zCnTSIBLLiUJrLxgdF5+CHQEzG9vuM9IalQ0b0PM5Dbp5BbLZSEff20giyqzhXvCRaQ0oPyXv3syejaENL2O2tIt/8KZpXZjWfO9cOLPDM/gNyY0QUG12jHdrpsPpzj8cPlIBJFIAAVMb5S6Yhr7fr8exjGLDg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782981254; c=relaxed/simple; bh=mYmmkuxBZ5QV9ShO/0+/hFRMIAfc93noWSRLe3YM/C0=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=RFL6ETzHLx+oYQsOlESN1jeElfZwdkD32YTZn9PMx1GOpuxcZ/MzGDykm9SG8n1Sc8q825nCdlxRsC3Y8mu+0LAkCcPCGqCeqkqmI03TclrH4PXM8sK0G769OkQtvv7n/Wz+3EsZUOdDz1wNQo3Q/uHpJBMCVo++nN+2/BVhKEw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h4KZcTME; 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="h4KZcTME" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EBC51F000E9; Thu, 2 Jul 2026 08:29:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1782981252; bh=S8GTPmmr03tsRZY5sQdF7Egz01B5e02T5y1C0rJ8lQY=; h=Subject:To:Cc:From:Date; b=h4KZcTMEgc3C6JcAmfIO/wXqVDrwhkRahYihclRRNBK5e7j0IhuwjSKk1YaBJ3lZS 7PGyHCaIwPS1YSAx2qkfi8NIMGBd7ARDw8AmP97OCSLaY3cEe9gbifdl+1517W+sOS +RrFIBMjSSoCWnFAT7IMr+0HlufRmeYO9DK2X9us= Subject: FAILED: patch "[PATCH] apparmor: fix use-after-free in rawdata dedup loop" failed to apply to 5.15-stable tree To: linuxoid@gmail.com,colin.i.king@gmail.com,john.johansen@canonical.com Cc: From: Date: Thu, 02 Jul 2026 10:29:20 +0200 Message-ID: <2026070220-ditto-skinny-d644@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 6f060496d03e4dc560a40f73770bd08335cb7a27 # git commit -s git send-email --to '' --in-reply-to '2026070220-ditto-skinny-d644@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6f060496d03e4dc560a40f73770bd08335cb7a27 Mon Sep 17 00:00:00 2001 From: Ruslan Valiyev Date: Tue, 26 May 2026 00:04:46 +0200 Subject: [PATCH] apparmor: fix use-after-free in rawdata dedup loop 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 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 847b0ff450c5..b59e827747da 100644 --- a/security/apparmor/policy.c +++ b/security/apparmor/policy.c @@ -1230,8 +1230,12 @@ 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;