From: Takashi Iwai tiwai@suse.de

stable inclusion from stable-v4.19.320 commit 643293b68fbb6c03f5e907736498da17d43f0d81 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAOXZ4 CVE: CVE-2024-44954

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit 15b7a03205b31bc5623378c190d22b7ff60026f1 upstream.

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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Conflicts: sound/usb/line6/driver.c [Fix context diff due to 6c764deba951 not merged] Signed-off-by: Yuan Can yuancan@huawei.com --- sound/usb/line6/driver.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c index bbcb0d4d83ae..6baa1dfcd0cd 100644 --- a/sound/usb/line6/driver.c +++ b/sound/usb/line6/driver.c @@ -300,12 +300,14 @@ 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);

@@ -314,11 +316,14 @@ 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); + spin_unlock_irqrestore(&line6->line6midi->lock, flags);

if (done == 0) break;