[3.16.y-ckt stable] Patch "ALSA: seq: Fix race at closing in virmidi driver" has been added to the 3.16.y-ckt tree
Luis Henriques
luis.henriques at canonical.com
Thu Feb 25 18:33:06 UTC 2016
This is a note to let you know that I have just added a patch titled
ALSA: seq: Fix race at closing in virmidi driver
to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue
This patch is scheduled to be released in version 3.16.7-ckt25.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
---8<------------------------------------------------------------
>From 49edef6e196465d6ab39aa55ea4c04542c4c4a99 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai at suse.de>
Date: Mon, 1 Feb 2016 12:06:42 +0100
Subject: ALSA: seq: Fix race at closing in virmidi driver
commit 2d1b5c08366acd46c35a2e9aba5d650cb5bf5c19 upstream.
The virmidi driver has an open race at closing its assigned rawmidi
device, and this may lead to use-after-free in
snd_seq_deliver_single_event().
Plug the hole by properly protecting the linked list deletion and
calling in the right order in snd_virmidi_input_close().
BugLink: http://lkml.kernel.org/r/CACT4Y+Zd66+w12fNN85-425cVQT=K23kWbhnCEcMB8s3us-Frw@mail.gmail.com
Reported-by: Dmitry Vyukov <dvyukov at google.com>
Tested-by: Dmitry Vyukov <dvyukov at google.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
sound/core/seq/seq_virmidi.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/sound/core/seq/seq_virmidi.c b/sound/core/seq/seq_virmidi.c
index 56e0f4cd3f82..f2975927551e 100644
--- a/sound/core/seq/seq_virmidi.c
+++ b/sound/core/seq/seq_virmidi.c
@@ -254,9 +254,13 @@ static int snd_virmidi_output_open(struct snd_rawmidi_substream *substream)
*/
static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream)
{
+ struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
struct snd_virmidi *vmidi = substream->runtime->private_data;
- snd_midi_event_free(vmidi->parser);
+
+ write_lock_irq(&rdev->filelist_lock);
list_del(&vmidi->list);
+ write_unlock_irq(&rdev->filelist_lock);
+ snd_midi_event_free(vmidi->parser);
substream->runtime->private_data = NULL;
kfree(vmidi);
return 0;
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