releases/3.18.114/alsa-hda-handle-kzalloc-failure-in-snd_hda_attach_pcm_stream.patch

   1 From a3aa60d511746bd6c0d0366d4eb90a7998bcde8b Mon Sep 17 00:00:00 2001
   2 From: Bo Chen <chenbo@pdx.edu>
   3 Date: Thu, 31 May 2018 15:35:18 -0700
   4 Subject: ALSA: hda - Handle kzalloc() failure in snd_hda_attach_pcm_stream()
   5
   6 From: Bo Chen <chenbo@pdx.edu>
   7
   8 commit a3aa60d511746bd6c0d0366d4eb90a7998bcde8b upstream.
   9
  10 When 'kzalloc()' fails in 'snd_hda_attach_pcm_stream()', a new pcm instance is
  11 created without setting its operators via 'snd_pcm_set_ops()'. Following
  12 operations on the new pcm instance can trigger kernel null pointer dereferences
  13 and cause kernel oops.
  14
  15 This bug was found with my work on building a gray-box fault-injection tool for
  16 linux-kernel-module binaries. A kernel null pointer dereference was confirmed
  17 from line 'substream->ops->open()' in function 'snd_pcm_open_substream()' in
  18 file 'sound/core/pcm_native.c'.
  19
  20 This patch fixes the bug by calling 'snd_device_free()' in the error handling
  21 path of 'kzalloc()', which removes the new pcm instance from the snd card before
  22 returns with an error code.
  23
  24 Signed-off-by: Bo Chen <chenbo@pdx.edu>
  25 Cc: <stable@vger.kernel.org>
  26 Signed-off-by: Takashi Iwai <tiwai@suse.de>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28
  29 ---
  30  sound/pci/hda/hda_controller.c |    4 +++-
  31  1 file changed, 3 insertions(+), 1 deletion(-)
  32
  33 --- a/sound/pci/hda/hda_controller.c
  34 +++ b/sound/pci/hda/hda_controller.c
  35 @@ -915,8 +915,10 @@ static int azx_attach_pcm_stream(struct
  36                 return err;
  37         strlcpy(pcm->name, cpcm->name, sizeof(pcm->name));
  38         apcm = kzalloc(sizeof(*apcm), GFP_KERNEL);
  39 -       if (apcm == NULL)
  40 +       if (apcm == NULL) {
  41 +               snd_device_free(chip->card, pcm);
  42                 return -ENOMEM;
  43 +       }
  44         apcm->chip = chip;
  45         apcm->pcm = pcm;
  46         apcm->codec = codec;