From 1dc8b65c944e5cfce3d830a5b97b42be185a1984 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 8 Jan 2020 11:00:00 +0100 Subject: [PATCH] media: v4l2-core: only zero-out ioctl-read buffers The memset() got moved out of the check for _IOC_NONE, so passing a made-up command number with a size but no direction would allow clearing data on user-provided pointers. Move video_get_user() back into the _IOC_NONE check where it belongs. Reported-by: syzbot+54fd8cca4b7226c94b8e@syzkaller.appspotmail.com Fixes: 6c625c01c7a6 ("media: v4l2-core: split out data copy from video_usercopy") Signed-off-by: Arnd Bergmann Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- drivers/media/v4l2-core/v4l2-ioctl.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c index b68ff06..aaf83e2 100644 --- a/drivers/media/v4l2-core/v4l2-ioctl.c +++ b/drivers/media/v4l2-core/v4l2-ioctl.c @@ -3205,12 +3205,12 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg, parg = mbuf; } + err = video_get_user((void __user *)arg, parg, orig_cmd, + &always_copy); + if (err) + goto out; } - err = video_get_user((void __user *)arg, parg, orig_cmd, &always_copy); - if (err) - goto out; - err = check_array_args(cmd, parg, &array_size, &user_ptr, &kernel_ptr); if (err < 0) goto out; -- 2.7.4