From nobody Mon Nov 25 05:54:18 2024 Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) (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 B2F9F1F131C; Wed, 30 Oct 2024 14:48:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=167.114.26.122 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730299700; cv=none; b=ZmcKm3YdklM0oO7T/NXPM0mje+Zz9oNjEitEijGYERN3tQ7DNGXuhb86bk9VjXhW6dmaz5GjnKbafpFI1Ka/0ome89i06nRSmc1UiY2xNoWQi8Qo6Bhl/TX1W4CwmWKQwKPsWrqTI56KQZY2L193jLE+m/9GAbQXud5g5F21ou8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730299700; c=relaxed/simple; bh=1JEthXtzxz6eAsr1v+U00Vn7zL7CFulinbZM6JAJ/10=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=CQ4V6zMFHviHg1I3r/qDm/Lr6ovN9moTFMCSl1EwS2aEZ6clW44SdjLu4mws6ky33yLtfmMKPzBTyFFUraOyL4w5hzx8W6OVMC2UPR4eFJ1oxgu94EzXl/fWbxZWbxdVCmsu5eYqHOXTN7iKXJlA/COZKeOFfdk/jtz5X4LrRgY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=lWvssXgc; arc=none smtp.client-ip=167.114.26.122 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="lWvssXgc" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1730299696; bh=1JEthXtzxz6eAsr1v+U00Vn7zL7CFulinbZM6JAJ/10=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lWvssXgc2LWJz4g0DqaUvIRnRsuc4aQ45HyV4oDyrxwl28721qb0f6anJciZB7yQR fpzWSI6F1dxK7XQ20YhApIj/ncXPdEmKm6wxc4kStNCgYMPBPl3NJBhvWNoS7E5J0t 1e3mL/lEO7R0wH1h1dgpsQK/sFb0lnciN1tK7ML4FkBviCm2mXFoV2Yv/r1/RXIBIT IxorV+W1lgwcOGLoOjAqLuIMwogFIVqRElTNAFOlZjnO0PxJmYnzOZLBL2dvjEliyp 07Cimiu+9ZCwCs1UwZ8AnBZD4cd5LSmhlNiNsb/c9FaybPqstfxx4/WrFhYpoSfF3M yBhBmzB6RcKqg== Received: from thinkos.internal.efficios.com (96-127-217-162.qc.cable.ebox.net [96.127.217.162]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4Xdqk84JyLzL8Q; Wed, 30 Oct 2024 10:48:16 -0400 (EDT) From: Mathieu Desnoyers To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers , Thomas Gleixner , Michael Jeanson , Masami Hiramatsu , Peter Zijlstra , Alexei Starovoitov , Yonghong Song , "Paul E . McKenney" , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Namhyung Kim , Andrii Nakryiko , bpf@vger.kernel.org, Joel Fernandes , Jordan Rife , syzbot+b390c8062d8387b6272a@syzkaller.appspotmail.com Subject: [PATCH v5 3/4] tracing: Fix syscall tracepoint use-after-free Date: Wed, 30 Oct 2024 10:46:33 -0400 Message-Id: <20241030144634.721630-4-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20241030144634.721630-1-mathieu.desnoyers@efficios.com> References: <20241030144634.721630-1-mathieu.desnoyers@efficios.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The grace period used internally within tracepoint.c:release_probes() uses call_rcu() to batch waiting for quiescence of old probe arrays, rather than using the tracepoint_synchronize_unregister() which blocks while waiting for quiescence. With the introduction of faultable syscall tracepoints, this causes use-after-free issues reproduced with syzkaller. Fix this by using the appropriate call_rcu() or call_rcu_tasks_trace() before invoking the rcu_free_old_probes callback. This can be chosen using the tracepoint_is_faultable() API. A similar issue exists in bpf use of call_rcu(). Fixing this is left to a separate change. Reported-by: syzbot+b390c8062d8387b6272a@syzkaller.appspotmail.com Fixes: a363d27cdbc2 ("tracing: Allow system call tracepoints to handle page= faults") Tested-by: Jordan Rife Signed-off-by: Mathieu Desnoyers Cc: Michael Jeanson Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Alexei Starovoitov Cc: Yonghong Song Cc: Paul E. McKenney Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Mark Rutland Cc: Alexander Shishkin Cc: Namhyung Kim Cc: Andrii Nakryiko Cc: bpf@vger.kernel.org Cc: Joel Fernandes Cc: Jordan Rife --- Changes since v0: - Introduce tracepoint_call_rcu(), - Fix bpf_link_free() use of call_rcu as well. Changes since v1: - Use tracepoint_call_rcu() for bpf_prog_put as well. Changes since v2: - Do not cover bpf changes in the same commit, let bpf developers implement it. Changes since v3: - Use tracepoint_is_faultable(). --- kernel/tracepoint.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 5658dc92f5b5..1848ce7e2976 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -106,13 +106,16 @@ static void rcu_free_old_probes(struct rcu_head *head) kfree(container_of(head, struct tp_probes, rcu)); } =20 -static inline void release_probes(struct tracepoint_func *old) +static inline void release_probes(struct tracepoint *tp, struct tracepoint= _func *old) { if (old) { struct tp_probes *tp_probes =3D container_of(old, struct tp_probes, probes[0]); =20 - call_rcu(&tp_probes->rcu, rcu_free_old_probes); + if (tracepoint_is_faultable(tp)) + call_rcu_tasks_trace(&tp_probes->rcu, rcu_free_old_probes); + else + call_rcu(&tp_probes->rcu, rcu_free_old_probes); } } =20 @@ -334,7 +337,7 @@ static int tracepoint_add_func(struct tracepoint *tp, break; } =20 - release_probes(old); + release_probes(tp, old); return 0; } =20 @@ -405,7 +408,7 @@ static int tracepoint_remove_func(struct tracepoint *tp, WARN_ON_ONCE(1); break; } - release_probes(old); + release_probes(tp, old); return 0; } =20 --=20 2.39.5