| Message ID | 1453124101-3402-1-git-send-email-drinkcat@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 > >
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);
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> --- sound/core/pcm_compat.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)