From nobody Thu Nov 28 17:54:30 2024 Received: from yyz.mikelr.com (yyz.mikelr.com [170.75.163.43]) (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 68D1118EAB; Sun, 29 Sep 2024 20:16:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.75.163.43 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727641004; cv=none; b=hcfMoDoMX9f+1Z6A2sIGJ22rugV4r1fWTuXQj6ms+405tTMfhsYfQ7EEjYMOrAXAey+l3bxIubAvOP/nvPwHQPTh9rKeIQSPtWrjnufnyDE6IozMp9m9TdjSdotMvUKvWTxbhJPCn1nDFTrQJitk8IyKSPbCSyDEHLc5VfFReAI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727641004; c=relaxed/simple; bh=tredQinZXruqSuQ7IrvoqP1PQHlHvSY4FpRmlPpn8dc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hxjt8alQCvg1SuGN8ak/hxm0QH9fnLSlcBnGOqYyifD4aB8OjVeSNh6XumPelxWktv7xfWRrvEl1MoZNsVKvOZIAdU+Q2kgAjNSQcN8y76UDA9DJTLAc5EWW2WjFb88+Fj615FVb+ImBVg8HzBQaGwsvr2Dl2z+BHBJJZPkKfjU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=mikelr.com; spf=pass smtp.mailfrom=mikelr.com; arc=none smtp.client-ip=170.75.163.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=mikelr.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mikelr.com Received: from basin.ykf.mikelr.com (unknown [IPv6:2607:f2c0:e554:1200:4b8f:795f:f483:85bf]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by yyz.mikelr.com (Postfix) with ESMTPSA id 0791271753; Sun, 29 Sep 2024 16:09:56 -0400 (EDT) From: Mikel Rychliski To: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers Cc: Mikel Rychliski , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH] tracing/probes: Fix MAX_TRACE_ARGS limit handling Date: Sun, 29 Sep 2024 16:09:37 -0400 Message-ID: <20240929200939.162524-1-mikel@mikelr.com> X-Mailer: git-send-email 2.46.1 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" When creating a trace_probe we would set nr_args prior to truncating the arguments to MAX_TRACE_ARGS. However, we would only initialize arguments up to the limit. This caused invalid memory access when attempting to set up probes with more than 128 fetchargs. BUG: kernel NULL pointer dereference, address: 0000000000000020 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 UID: 0 PID: 1769 Comm: cat Not tainted 6.11.0-rc7+ #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39= 04/01/2014 RIP: 0010:__set_print_fmt+0x134/0x330 Resolve the issue by applying the MAX_TRACE_ARGS limit earlier. This restores the prior behaviour of silently ignoring excess arguments. Fixes: 035ba76014c0 ("tracing/probes: cleanup: Set trace_probe::nr_args at = trace_probe_init") Signed-off-by: Mikel Rychliski --- kernel/trace/trace_eprobe.c | 5 +++-- kernel/trace/trace_fprobe.c | 3 ++- kernel/trace/trace_kprobe.c | 3 ++- kernel/trace/trace_uprobe.c | 3 ++- 4 files changed, 9 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c index b0e0ec85912e..62c1a1fba403 100644 --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -914,7 +914,7 @@ static int __trace_eprobe_create(int argc, const char *= argv[]) =20 mutex_lock(&event_mutex); event_call =3D find_and_get_event(sys_name, sys_event); - ep =3D alloc_event_probe(group, event, event_call, argc - 2); + ep =3D alloc_event_probe(group, event, event_call, min(argc - 2, MAX_TRAC= E_ARGS)); mutex_unlock(&event_mutex); =20 if (IS_ERR(ep)) { @@ -936,8 +936,9 @@ static int __trace_eprobe_create(int argc, const char *= argv[]) ep->filter_str =3D NULL; =20 argc -=3D 2; argv +=3D 2; + argc =3D min(argc, MAX_TRACE_ARGS); /* parse arguments */ - for (i =3D 0; i < argc && i < MAX_TRACE_ARGS; i++) { + for (i =3D 0; i < argc; i++) { trace_probe_log_set_index(i + 2); ret =3D trace_eprobe_tp_update_arg(ep, argv, i); if (ret) diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c index a079abd8955b..ca72fe8a04e7 100644 --- a/kernel/trace/trace_fprobe.c +++ b/kernel/trace/trace_fprobe.c @@ -1187,6 +1187,7 @@ static int __trace_fprobe_create(int argc, const char= *argv[]) argc =3D new_argc; argv =3D new_argv; } + argc =3D min(argc, MAX_TRACE_ARGS); =20 ret =3D traceprobe_expand_dentry_args(argc, argv, &dbuf); if (ret) @@ -1203,7 +1204,7 @@ static int __trace_fprobe_create(int argc, const char= *argv[]) } =20 /* parse arguments */ - for (i =3D 0; i < argc && i < MAX_TRACE_ARGS; i++) { + for (i =3D 0; i < argc; i++) { trace_probe_log_set_index(i + 2); ctx.offset =3D 0; ret =3D traceprobe_parse_probe_arg(&tf->tp, i, argv[i], &ctx); diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 61a6da808203..10d16b574db5 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1013,6 +1013,7 @@ static int __trace_kprobe_create(int argc, const char= *argv[]) argc =3D new_argc; argv =3D new_argv; } + argc =3D min(argc, MAX_TRACE_ARGS); =20 ret =3D traceprobe_expand_dentry_args(argc, argv, &dbuf); if (ret) @@ -1029,7 +1030,7 @@ static int __trace_kprobe_create(int argc, const char= *argv[]) } =20 /* parse arguments */ - for (i =3D 0; i < argc && i < MAX_TRACE_ARGS; i++) { + for (i =3D 0; i < argc; i++) { trace_probe_log_set_index(i + 2); ctx.offset =3D 0; ret =3D traceprobe_parse_probe_arg(&tk->tp, i, argv[i], &ctx); diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index c3df411a2684..985d23d57702 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -676,6 +676,7 @@ static int __trace_uprobe_create(int argc, const char *= *argv) =20 argc -=3D 2; argv +=3D 2; + argc =3D min(argc, MAX_TRACE_ARGS); =20 tu =3D alloc_trace_uprobe(group, event, argc, is_return); if (IS_ERR(tu)) { @@ -690,7 +691,7 @@ static int __trace_uprobe_create(int argc, const char *= *argv) tu->filename =3D filename; =20 /* parse arguments */ - for (i =3D 0; i < argc && i < MAX_TRACE_ARGS; i++) { + for (i =3D 0; i < argc; i++) { struct traceprobe_parse_context ctx =3D { .flags =3D (is_return ? TPARG_FL_RETURN : 0) | TPARG_FL_USER, }; base-commit: 886f3732878dc92fb0ad6d8b6740b66410d1d50a --=20 2.46.1