[PATCH] comedi: zero-init data in do_insn_ioctl

[Arnaud Lecomte]

KMSAN reported a kernel-infoleak when copying instruction data back to
userspace in do_insnlist_ioctl(). The issue occurs because allocated
memory buffers weren't properly initialized (not
zero initialized)  before being copied to
userspace, potentially leaking kernel memory.

Reported-by: syzbot+a5e45f768aab5892da5d@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=a5e45f768aab5892da5d
Tested-by: syzbot+a5e45f768aab5892da5d@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Arnaud Lecomte <contact@xxxxxxxxxxxxxx>
---
 drivers/comedi/comedi_fops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c
index c83fd14dd7ad..15fee829d14c 100644
--- a/drivers/comedi/comedi_fops.c
+++ b/drivers/comedi/comedi_fops.c
@@ -1636,7 +1636,7 @@ static int do_insn_ioctl(struct comedi_device *dev,
 		n_data = MAX_SAMPLES;
 	}
 
-	data = kmalloc_array(n_data, sizeof(unsigned int), GFP_KERNEL);
+	data = kcalloc(n_data, sizeof(unsigned int), GFP_KERNEL);
 	if (!data) {
 		ret = -ENOMEM;
 		goto error;
-- 
2.43.0