Messages in this thread Patch in this message | | | Date | Fri, 04 Mar 2016 16:30:38 +0100 | From | Willy Tarreau <> | Subject | [PATCH 2.6.32 38/55] ALSA: seq: Fix race at closing in virmidi driver |
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2.6.32-longterm review patch. If anyone has any objections, please let me know.
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From: Takashi Iwai <tiwai@suse.de>
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@google.com> Tested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Willy Tarreau <w@1wt.eu> --- 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 86e7739..081a099 100644 --- a/sound/core/seq/seq_virmidi.c +++ b/sound/core/seq/seq_virmidi.c @@ -253,9 +253,13 @@ 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; -- 1.7.12.2.21.g234cd45.dirty
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