On Mon, 18 Jan 2016 14:35:00 +0100, Nicolas Boichat wrote:
This reverts one hunk of commit ef44a1ec6eee ("ALSA: sound/core: use memdup_user()"), which replaced a number of kmalloc followed by memcpy with memdup calls.
In this case, we are copying from a struct snd_pcm_hw_params32 to a struct snd_pcm_hw_params, but the latter is 4 bytes longer than the 32-bit version, so we need to separate kmalloc and copy calls.
This actually leads to an out-of-bounds memory access later on in sound/soc/soc-pcm.c:soc_pcm_hw_params() (detected using KASan).
Signed-off-by: Nicolas Boichat drinkcat@chromium.org
Applied both patches with Cc to stable. Thanks.
Takashi
sound/core/pcm_compat.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c index b48b434..9630e9f 100644 --- a/sound/core/pcm_compat.c +++ b/sound/core/pcm_compat.c @@ -255,10 +255,15 @@ static int snd_pcm_ioctl_hw_params_compat(struct snd_pcm_substream *substream, if (! (runtime = substream->runtime)) return -ENOTTY;
- /* only fifo_size is different, so just copy all */
- data = memdup_user(data32, sizeof(*data32));
- if (IS_ERR(data))
return PTR_ERR(data);
data = kmalloc(sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;/* only fifo_size (RO from userspace) is different, so just copy all */
if (copy_from_user(data, data32, sizeof(*data32))) {
err = -EFAULT;goto error;}
if (refine) err = snd_pcm_hw_refine(substream, data);
-- 2.6.0.rc2.230.g3dd15c0