The patch below does not apply to the 5.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From e926c474ebee404441c838d18224cd6f246a71b7 Mon Sep 17 00:00:00 2001
From: Daniel Vetter daniel.vetter@ffwll.ch Date: Mon, 22 Feb 2021 11:06:43 +0100 Subject: [PATCH] drm/compat: Clear bounce structures
Some of them have gaps, or fields we don't clear. Native ioctl code does full copies plus zero-extends on size mismatch, so nothing can leak. But compat is more hand-rolled so need to be careful.
None of these matter for performance, so just memset.
Also I didn't fix up the CONFIG_DRM_LEGACY or CONFIG_DRM_AGP ioctl, those are security holes anyway.
Acked-by: Maxime Ripard mripard@kernel.org Reported-by: syzbot+620cf21140fc7e772a5d@syzkaller.appspotmail.com # vblank ioctl Cc: syzbot+620cf21140fc7e772a5d@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter daniel.vetter@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20210222100643.400935-1-daniel...
diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c index f86448ab1fe0..dc734d4828a1 100644 --- a/drivers/gpu/drm/drm_ioc32.c +++ b/drivers/gpu/drm/drm_ioc32.c @@ -99,6 +99,8 @@ static int compat_drm_version(struct file *file, unsigned int cmd, if (copy_from_user(&v32, (void __user *)arg, sizeof(v32))) return -EFAULT;
+ memset(&v, 0, sizeof(v)); + v = (struct drm_version) { .name_len = v32.name_len, .name = compat_ptr(v32.name), @@ -137,6 +139,9 @@ static int compat_drm_getunique(struct file *file, unsigned int cmd,
if (copy_from_user(&uq32, (void __user *)arg, sizeof(uq32))) return -EFAULT; + + memset(&uq, 0, sizeof(uq)); + uq = (struct drm_unique){ .unique_len = uq32.unique_len, .unique = compat_ptr(uq32.unique), @@ -265,6 +270,8 @@ static int compat_drm_getclient(struct file *file, unsigned int cmd, if (copy_from_user(&c32, argp, sizeof(c32))) return -EFAULT;
+ memset(&client, 0, sizeof(client)); + client.idx = c32.idx;
err = drm_ioctl_kernel(file, drm_getclient, &client, 0); @@ -852,6 +859,8 @@ static int compat_drm_wait_vblank(struct file *file, unsigned int cmd, if (copy_from_user(&req32, argp, sizeof(req32))) return -EFAULT;
+ memset(&req, 0, sizeof(req)); + req.request.type = req32.request.type; req.request.sequence = req32.request.sequence; req.request.signal = req32.request.signal; @@ -889,6 +898,8 @@ static int compat_drm_mode_addfb2(struct file *file, unsigned int cmd, struct drm_mode_fb_cmd2 req64; int err;
+ memset(&req64, 0, sizeof(req64)); + if (copy_from_user(&req64, argp, offsetof(drm_mode_fb_cmd232_t, modifier))) return -EFAULT;