From nobody Wed Dec 17 08:54:48 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1485019C556; Sat, 10 May 2025 03:44:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746848687; cv=none; b=NntXdyuu2JlHzRp1B7kqT+PANW3yoFxTs7CdFQxYxNRu8dzSicRJ9QVGf47UmkuT3XzJDXZVB/dZMg7A6bRF77bfz/arGf6OSRe+FY/EBII9BVVaaVeqBTDEzimEpJzofs9BPsW8HvcjlVmzf8DhGC3DLtXQxQQTTquff/Sreyk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746848687; c=relaxed/simple; bh=lJZMKARAdrlkZTQd04Ofxb+YfDhSi6CN4YD16dHYFsE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=EISq90KH2XtVuB0L9J9KgGsrVvAnapfyr0WhdSttlcQHm8XdO4wAZZSp1msrAYr0Yq6vIIoJIH3uvw5/UPtzHM1o1H700qdvJJ60x+kw0DiBh23TOjpA2C/M7zdm4FIPvtHB7UFQ+fzqzexRKhNdf/ji/bro9ewoUddb8VzXsXI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Y0B7rA63; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Y0B7rA63" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB9E2C4CEE2; Sat, 10 May 2025 03:44:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746848685; bh=lJZMKARAdrlkZTQd04Ofxb+YfDhSi6CN4YD16dHYFsE=; h=From:To:Cc:Subject:Date:From; b=Y0B7rA632mHKyXt7Vt4nCU2+YBEpSzFc4SWaYnxjjFWcb21ZS9ynLWOIueEx6I7z5 y+pfKiaRe8U1QJXfjXAfmgG80HWxEV+0rMG9I+nWQ9EWCjVLPeu9En2L5KfRqw/qHa t7PNLxXqQcN6qbMr17mX9AnXziuNHNBjGbrHzhYfsrTaBoopFWcnreHaIC/DEG3pRT byh7psw4HItZQMPQp6C16nEXnxEXaBZ9qjaC66032FPm74JTvONHdgQr3bj0WIgAaY WmoceLpSrqNXf2dO5dJLTyhfPy456DbJOCHcHGftZsTaJHsr/4aET53UQlgWKQ0xl5 zJj2P16U2pFeQ== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Paul Cacheux Cc: Masami Hiramatsu , Mathieu Desnoyers , Namhyung Kim , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH] tracing: probes: Fix a possible race in trace_probe_log APIs Date: Sat, 10 May 2025 12:44:41 +0900 Message-ID: <174684868120.551552.3068655787654268804.stgit@devnote2> X-Mailer: git-send-email 2.43.0 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Since the shared trace_probe_log variable can be accessed and modified via probe event create operation of kprobe_events, uprobe_events, and dynamic_events, it should be protected. In the dynamic_events, all operations are serialized by `dyn_event_ops_mutex`. But kprobe_events and uprobe_events interfaces are not serialized. To solve this issue, introduces dyn_event_create(), which runs create() operation under the mutex, for kprobe_events and uprobe_events. This also uses lockdep to check the mutex is held when using trace_probe_log* APIs. Reported-by: Paul Cacheux Closes: https://lore.kernel.org/all/20250510074456.805a16872b591e2971a4d221= @kernel.org/ Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_dynevent.c | 16 +++++++++++++++- kernel/trace/trace_dynevent.h | 1 + kernel/trace/trace_kprobe.c | 2 +- kernel/trace/trace_probe.c | 9 +++++++++ kernel/trace/trace_uprobe.c | 2 +- 5 files changed, 27 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c index a322e4f249a5..5d64a18cacac 100644 --- a/kernel/trace/trace_dynevent.c +++ b/kernel/trace/trace_dynevent.c @@ -16,7 +16,7 @@ #include "trace_output.h" /* for trace_event_sem */ #include "trace_dynevent.h" =20 -static DEFINE_MUTEX(dyn_event_ops_mutex); +DEFINE_MUTEX(dyn_event_ops_mutex); static LIST_HEAD(dyn_event_ops_list); =20 bool trace_event_dyn_try_get_ref(struct trace_event_call *dyn_call) @@ -116,6 +116,20 @@ int dyn_event_release(const char *raw_command, struct = dyn_event_operations *type return ret; } =20 +/* + * Locked version of event creation. The event creation must be protected = by + * dyn_event_ops_mutex because of protecting trace_probe_log. + */ +int dyn_event_create(const char *raw_command, struct dyn_event_operations = *type) +{ + int ret; + + mutex_lock(&dyn_event_ops_mutex); + ret =3D type->create(raw_command); + mutex_unlock(&dyn_event_ops_mutex); + return ret; +} + static int create_dyn_event(const char *raw_command) { struct dyn_event_operations *ops; diff --git a/kernel/trace/trace_dynevent.h b/kernel/trace/trace_dynevent.h index 936477a111d3..beee3f8d7544 100644 --- a/kernel/trace/trace_dynevent.h +++ b/kernel/trace/trace_dynevent.h @@ -100,6 +100,7 @@ void *dyn_event_seq_next(struct seq_file *m, void *v, l= off_t *pos); void dyn_event_seq_stop(struct seq_file *m, void *v); int dyn_events_release_all(struct dyn_event_operations *type); int dyn_event_release(const char *raw_command, struct dyn_event_operations= *type); +int dyn_event_create(const char *raw_command, struct dyn_event_operations = *type); =20 /* * for_each_dyn_event - iterate over the dyn_event list diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 2703b96d8990..3e5c47b6d7b2 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1089,7 +1089,7 @@ static int create_or_delete_trace_kprobe(const char *= raw_command) if (raw_command[0] =3D=3D '-') return dyn_event_release(raw_command, &trace_kprobe_ops); =20 - ret =3D trace_kprobe_create(raw_command); + ret =3D dyn_event_create(raw_command, &trace_kprobe_ops); return ret =3D=3D -ECANCELED ? -EINVAL : ret; } =20 diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 2eeecb6c95ee..424751cdf31f 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -154,9 +154,12 @@ static const struct fetch_type *find_fetch_type(const = char *type, unsigned long } =20 static struct trace_probe_log trace_probe_log; +extern struct mutex dyn_event_ops_mutex; =20 void trace_probe_log_init(const char *subsystem, int argc, const char **ar= gv) { + lockdep_assert_held(&dyn_event_ops_mutex); + trace_probe_log.subsystem =3D subsystem; trace_probe_log.argc =3D argc; trace_probe_log.argv =3D argv; @@ -165,11 +168,15 @@ void trace_probe_log_init(const char *subsystem, int = argc, const char **argv) =20 void trace_probe_log_clear(void) { + lockdep_assert_held(&dyn_event_ops_mutex); + memset(&trace_probe_log, 0, sizeof(trace_probe_log)); } =20 void trace_probe_log_set_index(int index) { + lockdep_assert_held(&dyn_event_ops_mutex); + trace_probe_log.index =3D index; } =20 @@ -178,6 +185,8 @@ void __trace_probe_log_err(int offset, int err_type) char *command, *p; int i, len =3D 0, pos =3D 0; =20 + lockdep_assert_held(&dyn_event_ops_mutex); + if (!trace_probe_log.argv) return; =20 diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 3386439ec9f6..35cf76c75dd7 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -741,7 +741,7 @@ static int create_or_delete_trace_uprobe(const char *ra= w_command) if (raw_command[0] =3D=3D '-') return dyn_event_release(raw_command, &trace_uprobe_ops); =20 - ret =3D trace_uprobe_create(raw_command); + ret =3D dyn_event_create(raw_command, &trace_uprobe_ops); return ret =3D=3D -ECANCELED ? -EINVAL : ret; }