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authorTakashi Iwai <tiwai@suse.de>2024-08-05 15:01:28 +0200
committerTakashi Iwai <tiwai@suse.de>2024-08-05 15:03:03 +0200
commit15b7a03205b31bc5623378c190d22b7ff60026f1 (patch)
tree5c200455693b47ee319ff706404ff0d98c4bdcfe
parent312c04cee408a8448ec8b639fe7f0434017d7161 (diff)
ALSA: line6: Fix racy access to midibuf
There can be concurrent accesses to line6 midibuf from both the URB completion callback and the rawmidi API access. This could be a cause of KMSAN warning triggered by syzkaller below (so put as reported-by here). This patch protects the midibuf call of the former code path with a spinlock for avoiding the possible races. Reported-by: syzbot+78eccfb8b3c9a85fc6c5@syzkaller.appspotmail.com Closes: https://lore.kernel.org/00000000000000949c061df288c5@google.com Cc: <stable@vger.kernel.org> Link: https://patch.msgid.link/20240805130129.10872-1-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/usb/line6/driver.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c
index f4437015d43a..9df49a880b75 100644
--- a/sound/usb/line6/driver.c
+++ b/sound/usb/line6/driver.c
@@ -286,12 +286,14 @@ static void line6_data_received(struct urb *urb)
{
struct usb_line6 *line6 = (struct usb_line6 *)urb->context;
struct midi_buffer *mb = &line6->line6midi->midibuf_in;
+ unsigned long flags;
int done;
if (urb->status == -ESHUTDOWN)
return;
if (line6->properties->capabilities & LINE6_CAP_CONTROL_MIDI) {
+ spin_lock_irqsave(&line6->line6midi->lock, flags);
done =
line6_midibuf_write(mb, urb->transfer_buffer, urb->actual_length);
@@ -300,12 +302,15 @@ static void line6_data_received(struct urb *urb)
dev_dbg(line6->ifcdev, "%d %d buffer overflow - message skipped\n",
done, urb->actual_length);
}
+ spin_unlock_irqrestore(&line6->line6midi->lock, flags);
for (;;) {
+ spin_lock_irqsave(&line6->line6midi->lock, flags);
done =
line6_midibuf_read(mb, line6->buffer_message,
LINE6_MIDI_MESSAGE_MAXLEN,
LINE6_MIDIBUF_READ_RX);
+ spin_unlock_irqrestore(&line6->line6midi->lock, flags);
if (done <= 0)
break;