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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Takashi Iwai <tiwai@suse.de>,
	syzbot+cce32521ee0a824c21f7@syzkaller.appspotmail.com,
	Sasha Levin <sashal@kernel.org>,
	alsa-devel@alsa-project.org
Subject: [PATCH AUTOSEL 5.4 16/19] ALSA: line6: Fix endless MIDI read loop
Date: Thu, 26 Mar 2020 19:24:28 -0400
Message-ID: <20200326232431.7816-16-sashal@kernel.org> (raw)
In-Reply-To: <20200326232431.7816-1-sashal@kernel.org>

From: Takashi Iwai <tiwai@suse.de>

[ Upstream commit d683469b3c93d7e2afd39e6e1970f24700eb7a68 ]

The MIDI input event parser of the LINE6 driver may enter into an
endless loop when the unexpected data sequence is given, as it tries
to continue the secondary bytes without termination.  Also, when the
input data is too short, the parser returns a negative error, while
the caller doesn't handle it properly.  This would lead to the
unexpected behavior as well.

This patch addresses those issues by checking the return value
correctly and handling the one-byte event in the parser properly.

The bug was reported by syzkaller.

Reported-by: syzbot+cce32521ee0a824c21f7@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/000000000000033087059f8f8fa3@google.com
Link: https://lore.kernel.org/r/20200309095922.30269-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/usb/line6/driver.c  | 2 +-
 sound/usb/line6/midibuf.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c
index b5a3f754a4f13..4f096685ed654 100644
--- a/sound/usb/line6/driver.c
+++ b/sound/usb/line6/driver.c
@@ -305,7 +305,7 @@ static void line6_data_received(struct urb *urb)
 				line6_midibuf_read(mb, line6->buffer_message,
 						LINE6_MIDI_MESSAGE_MAXLEN);
 
-			if (done == 0)
+			if (done <= 0)
 				break;
 
 			line6->message_length = done;
diff --git a/sound/usb/line6/midibuf.c b/sound/usb/line6/midibuf.c
index 8d6eefa0d9362..6a70463f82c4e 100644
--- a/sound/usb/line6/midibuf.c
+++ b/sound/usb/line6/midibuf.c
@@ -159,7 +159,7 @@ int line6_midibuf_read(struct midi_buffer *this, unsigned char *data,
 			int midi_length_prev =
 			    midibuf_message_length(this->command_prev);
 
-			if (midi_length_prev > 0) {
+			if (midi_length_prev > 1) {
 				midi_length = midi_length_prev - 1;
 				repeat = 1;
 			} else
-- 
2.20.1


  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26 23:24 [PATCH AUTOSEL 5.4 01/19] drm/bridge: dw-hdmi: fix AVI frame colorimetry Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 02/19] nvme-rdma: Avoid double freeing of async event data Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 03/19] ALSA: hda/realtek: Fix pop noise on ALC225 Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 04/19] kconfig: introduce m32-flag and m64-flag Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 05/19] drm/amd/display: Add link_rate quirk for Apple 15" MBP 2017 Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 06/19] drm/bochs: downgrade pci_request_region failure from error to warning Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 07/19] initramfs: restore default compression behavior Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 08/19] staging: greybus: loopback_test: fix potential path truncation Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 09/19] staging: greybus: loopback_test: fix potential path truncations Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 10/19] drm/amdgpu: fix typo for vcn1 idle check Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 11/19] tools/power turbostat: Fix gcc build warnings Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 12/19] tools/power turbostat: Fix missing SYS_LPI counter on some Chromebooks Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 13/19] tools/power turbostat: Fix 32-bit capabilities warning Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 14/19] nvmet-tcp: set MSG_MORE only if we actually have more to send Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 15/19] ALSA: pcm: oss: Avoid plugin buffer overflow Sasha Levin
2020-03-26 23:24 ` Sasha Levin [this message]
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 17/19] ALSA: pcm: oss: Remove WARNING from snd_pcm_plug_alloc() checks Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 18/19] tty: fix compat TIOCGSERIAL leaking uninitialized memory Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 19/19] drm/lease: fix WARNING in idr_destroy Sasha Levin

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