From 3abab27c322e0f2acf981595aa8040c9164dc9fb Mon Sep 17 00:00:00 2001 From: Charles Baylis Date: Fri, 16 Jul 2021 17:43:12 +0100 Subject: [PATCH] drm: Return -ENOTTY for non-drm ioctls drm: Return -ENOTTY for non-drm ioctls Return -ENOTTY from drm_ioctl() when userspace passes in a cmd number which doesn't relate to the drm subsystem. Glibc uses the TCGETS ioctl to implement isatty(), and without this change isatty() returns it incorrectly returns true for drm devices. To test run this command: $ if [ -t 0 ]; then echo is a tty; fi < /dev/dri/card0 which shows "is a tty" without this patch. This may also modify memory which the userspace application is not expecting. Signed-off-by: Charles Baylis Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/YPG3IBlzaMhfPqCr@stando.fishzet.co.uk --- drivers/gpu/drm/drm_ioctl.c | 3 +++ include/drm/drm_ioctl.h | 1 + 2 files changed, 4 insertions(+) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 98ae006616565..f454e04240860 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -834,6 +834,9 @@ long drm_ioctl(struct file *filp, if (drm_dev_is_unplugged(dev)) return -ENODEV; + if (DRM_IOCTL_TYPE(cmd) != DRM_IOCTL_BASE) + return -ENOTTY; + is_driver_ioctl = nr >= DRM_COMMAND_BASE && nr < DRM_COMMAND_END; if (is_driver_ioctl) { diff --git a/include/drm/drm_ioctl.h b/include/drm/drm_ioctl.h index 10100a4bbe2ad..afb27cb6a7bd8 100644 --- a/include/drm/drm_ioctl.h +++ b/include/drm/drm_ioctl.h @@ -68,6 +68,7 @@ typedef int drm_ioctl_compat_t(struct file *filp, unsigned int cmd, unsigned long arg); #define DRM_IOCTL_NR(n) _IOC_NR(n) +#define DRM_IOCTL_TYPE(n) _IOC_TYPE(n) #define DRM_MAJOR 226 /** -- 2.30.2