From patchwork Sat Oct 26 15:46:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathieu Desnoyers X-Patchwork-Id: 13852270 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 7D9817082C; Sat, 26 Oct 2024 15:48:15 +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=1729957699; cv=none; b=YLSyYuf1jGh4LU/UaECecOhl5h/OrsP7QmAlGnjh64SiCuUOW7/jIhnXozpkKr8AiyeU1ruW+lPkXlrnylEtFXF/bTDU3L6/NlKtZ/fetHcZVd4i4bU11L+ntZjYwNxUssEOPiXeAdzbIHgJvX1GEF5aKwN73YfXPN5NuM68Ruc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729957699; c=relaxed/simple; bh=mP2SnazjhRJn11GZWVw23pPFqpTRRLfPTVW/ACXPM/M=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=tEtIg0YXEtC8V6EPR8n/TDdmSZq8rBf3SJZqbOT0ePNz6zTgTvRY7/J7L1ui6qH98ccTurEMXWU2betgZR0TYBV12FRzeE8SjhNV2JrX2r5t4aDzIDKp+qFK7Ok75lcDwRnTZAvHA/BKMevgu6CT5vPD1CXPFcAfctP+SPnmatQ= 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=WkI243QA; 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="WkI243QA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1729957694; bh=mP2SnazjhRJn11GZWVw23pPFqpTRRLfPTVW/ACXPM/M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WkI243QAgP/1+HAbl6jg9BO3I5WlscoGIdV+jSAB8hajaCAOu+FtOoHqVZD9gzhiX tnFRi49Bl/2BnJXVagz/TxtZEmRyflC9GrbbyTs4OE2WBcJmgAWltaa4x5MlYIdFF+ 59Cblqrf5VojmZnZM8dQogtSziWXotcgCIxZQLFM/bkaoSWqDiYzwq3MpZ6kQ3n9mh VRL1mRTxs6MX675IKU+b7xPB0mQ2nMJkC6BlXLOYJPhMIngHEb8B44HZ3CCvUOTP46 W7Z3JSuuMlkJKmkvG9p49u8IvJHDdiRPMYNW2rNMWD/B5JWYgbaifnToiqcHFNJKkF 6AUmJwOzqt9HQ== Received: from thinkos.internal.efficios.com (unknown [IPv6:2606:6d00:100:4000:cacb:9855:de1f:ded2]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4XbPFB126RzNmP; Sat, 26 Oct 2024 11:48:14 -0400 (EDT) From: Mathieu Desnoyers To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers , 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: [RFC PATCH v3 3/3] tracing: Fix syscall tracepoint use-after-free Date: Sat, 26 Oct 2024 11:46:29 -0400 Message-Id: <20241026154629.593041-3-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20241026154629.593041-1-mathieu.desnoyers@efficios.com> References: <20241026154629.593041-1-mathieu.desnoyers@efficios.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-State: RFC 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_syscall() 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") 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. --- kernel/tracepoint.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 5658dc92f5b5..47569fb06596 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)); } -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 = container_of(old, struct tp_probes, probes[0]); - call_rcu(&tp_probes->rcu, rcu_free_old_probes); + if (tracepoint_is_syscall(tp)) + call_rcu_tasks_trace(&tp_probes->rcu, rcu_free_old_probes); + else + call_rcu(&tp_probes->rcu, rcu_free_old_probes); } } @@ -334,7 +337,7 @@ static int tracepoint_add_func(struct tracepoint *tp, break; } - release_probes(old); + release_probes(tp, old); return 0; } @@ -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; }