In current implementation, for I/O request of ELEM_INFO, kernel stack
is used to copy 'struct snd_ctl_elem_info' data. However, the size of
this structure is a bit big and usage of kernel stack is not preferable.
This commit allocates a memory object on kernel space, instead.
Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
---
sound/core/control.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)
diff --git a/sound/core/control.c b/sound/core/control.c
index 8d158a49467d..4cb950e310bf 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -875,20 +875,23 @@ static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
return result;
}
-static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
- struct snd_ctl_elem_info __user *_info)
+static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl, void __user *arg)
{
- struct snd_ctl_elem_info info;
- int result;
+ struct snd_ctl_elem_info *info;
+ int err;
- if (copy_from_user(&info, _info, sizeof(info)))
- return -EFAULT;
- result = snd_ctl_elem_info(ctl, &info);
- if (result < 0)
- return result;
- if (copy_to_user(_info, &info, sizeof(info)))
- return -EFAULT;
- return result;
+ info = memdup_user(arg, sizeof(*info));
+ if (IS_ERR(info))
+ return PTR_ERR(info);
+
+ err = snd_ctl_elem_info(ctl, info);
+ if (err >= 0) {
+ if (copy_to_user(arg, info, sizeof(*info)))
+ return -EFAULT;
+ }
+
+ kfree(info);
+ return err;
}
static int snd_ctl_elem_read(struct snd_card *card,
--
2.14.1
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