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 2A7061CAA6D; Tue, 21 Jul 2026 18:09:37 +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=1784657379; cv=none; b=Hvg8ql1PQMo2LykvSz3pM2aSq0i90Ptc0VmWlhTQLGTKHpW+9JwAOVtX8HxM8CCKz7KloTj67vijAlqtq/D6CrGdIdWV/JHMu4ciDe790w5ibWp+KlpG+0pzflK4HM1kL0rquK878RIt1pZWIsZ6/BFhJbwgbp5oMwyArS57dr4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784657379; c=relaxed/simple; bh=KB2p9MNx6EZxXBIVFoa9LHDG72E6zkSq3FZasHT/NZA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pJPMrp4zP33Ns1mWVuw0SEYbJw78F77fULmSLB3epKTa0PWfY01Hu5yy+bobxCAJsen9Rhvv+KH2zbhvYOtfQTmY7g0+TPZMNRunzn79UpjT4rE3jN0oZe3OmSSkuSN/tlEAporFv29oweOGuLeeOjEq2rUc54YMKxKjHCuCu2o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=I61WOW1+; 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="I61WOW1+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 470821F00A3A; Tue, 21 Jul 2026 18:09:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784657377; bh=IV251Hv9SK2vPjBYBPsxK1AXg3rNBhl4o/LYKaxZKME=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=I61WOW1+N1dkTTkRDIqJCY/wUAwenm/Vm3fLhF86pQJJ/nYEQsj3+hS2Fn19s7gKf YDG2cI16emyltJfZDC8yo1i4DOZUM98dcAAgbGivkZAGMVvr7XUlwnBPLTif0fRhAC smaxC0cafRuJkKW5za+WPLpZdOcREb7qyRxUbUxU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Georgia Garcia , Ryan Lee , John Johansen , Sasha Levin Subject: [PATCH 6.18 0740/1611] apparmor: grab ns lock and refresh when looking up changehat child profiles Date: Tue, 21 Jul 2026 17:14:16 +0200 Message-ID: <20260721152532.020996227@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@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: Ryan Lee [ Upstream commit 32e92764d6f8d251c1bca62be33793287b453a81 ] There was a race condition involving change_hat and profile replacement in which replacement of the parent profile during a changehat operation could result in the list of children becoming empty and the changehat operation failing. To prevent this: - grab the namespace lock until we've built the hat transition, and - use aa_get_newest_profile to avoid using stale profile objects. Link: https://bugs.launchpad.net/bugs/2139664 Fixes: 89dbf1962aa63 ("apparmor: move change_hat mediation to using labels") Reviewed-by: Georgia Garcia Signed-off-by: Ryan Lee Signed-off-by: John Johansen Signed-off-by: Sasha Levin --- security/apparmor/domain.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c index cc54c1205efe82..cf9feed1306dea 100644 --- a/security/apparmor/domain.c +++ b/security/apparmor/domain.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -1107,6 +1108,7 @@ static struct aa_label *change_hat(const struct cred *subj_cred, int count, int flags) { struct aa_profile *profile, *root, *hat = NULL; + struct aa_ns *ns, *new_ns; struct aa_label *new; struct label_it it; bool sibling = false; @@ -1117,6 +1119,32 @@ static struct aa_label *change_hat(const struct cred *subj_cred, AA_BUG(!hats); AA_BUG(count < 1); + /* + * Acquire the newest label and then hold the lock until we choose a + * hat, so that profile replacement doesn't atomically truncate the + * list of potential hats. Because we are getting the namespaces from + * the profiles and label, we can rely on the namespaces being live + * and avoid incrementing their refcounts while grabbing the lock. + */ + label = aa_get_label(label); + ns = labels_ns(label); + +retry: + mutex_lock_nested(&ns->lock, ns->level); + if (label_is_stale(label)) { + new = aa_get_newest_label(label); + new_ns = labels_ns(new); + if (new_ns != ns) { + aa_put_label(new); + mutex_unlock(&ns->lock); + ns = new_ns; + label = new; + goto retry; + } + aa_put_label(label); + label = new; + } + if (PROFILE_IS_HAT(labels_profile(label))) sibling = true; @@ -1125,7 +1153,7 @@ static struct aa_label *change_hat(const struct cred *subj_cred, name = hats[i]; label_for_each_in_ns(it, labels_ns(label), label, profile) { if (sibling && PROFILE_IS_HAT(profile)) { - root = aa_get_profile_rcu(&profile->parent); + root = aa_get_profile(profile->parent); } else if (!sibling && !PROFILE_IS_HAT(profile)) { root = aa_get_profile(profile); } else { /* conflicting change type */ @@ -1185,6 +1213,7 @@ static struct aa_label *change_hat(const struct cred *subj_cred, GLOBAL_ROOT_UID, info, error); } } + mutex_unlock(&ns->lock); return ERR_PTR(error); build: @@ -1197,7 +1226,7 @@ static struct aa_label *change_hat(const struct cred *subj_cred, error = -ENOMEM; goto fail; } /* else if (IS_ERR) build_change_hat has logged error so return new */ - + mutex_unlock(&ns->lock); return new; } -- 2.53.0