[PATCH 4.2.y-ckt 165/268] ALSA: seq: Fix snd_seq_call_port_info_ioctl in compat mode

From: Kamal Mostafa
Date: Wed Jan 27 2016 - 16:21:46 EST

4.2.8-ckt3 -stable review patch. If anyone has any objections, please let me know.


From: Nicolas Boichat <drinkcat@xxxxxxxxxxxx>

commit 9586495dc3011a80602329094e746dbce16cb1f1 upstream.

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_seq_port_info32 to a
struct snd_seq_port_info, but the latter is 4 bytes longer than the
32-bit version, so we need to separate kmalloc and copy calls.

Fixes: ef44a1ec6eee ('ALSA: sound/core: use memdup_user()')
Signed-off-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
sound/core/seq/seq_compat.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/sound/core/seq/seq_compat.c b/sound/core/seq/seq_compat.c
index 81f7c10..6517590 100644
--- a/sound/core/seq/seq_compat.c
+++ b/sound/core/seq/seq_compat.c
@@ -49,11 +49,12 @@ static int snd_seq_call_port_info_ioctl(struct snd_seq_client *client, unsigned
struct snd_seq_port_info *data;
mm_segment_t fs;

- data = memdup_user(data32, sizeof(*data32));
- if (IS_ERR(data))
- return PTR_ERR(data);
+ data = kmalloc(sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;

- if (get_user(data->flags, &data32->flags) ||
+ if (copy_from_user(data, data32, sizeof(*data32)) ||
+ get_user(data->flags, &data32->flags) ||
get_user(data->time_queue, &data32->time_queue))
goto error;
data->kernel = NULL;