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| author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2018-08-22 10:54:04 +0200 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2018-09-11 14:11:54 +0200 |
| commit | da6c7707caf3736c1cf968606bd97c07e79625d4 (patch) | |
| tree | a8b9621e30d58b35c3547a17d753962ddbeeecde /drivers | |
| parent | 8d7fc2994f4d1f431e280c9e21a139c18dc435ec (diff) | |
| download | linux-da6c7707caf3736c1cf968606bd97c07e79625d4.tar.gz | |
fbdev: Add FBINFO_HIDE_SMEM_START flag
DRM drivers really, really, really don't want random userspace to share buffer behind it's back, bypassing the dma-buf buffer sharing machanism. For that reason we've ruthlessly rejected any IOCTL exposing the physical address of any graphics buffer. Unfortunately fbdev comes with that built-in. We could just set smem_start to 0, but that means we'd have to hand-roll our own fb_mmap implementation. For good reasons many drivers do that, but smem_start/length is still super convenient. Hence instead just stop the leak in the ioctl, to keep fb mmap working as-is. A second patch will set this flag for all drm drivers. Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Kees Cook <keescook@chromium.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: linux-fbdev@vger.kernel.org Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180822085405.10787-3-daniel.vetter@ffwll.ch
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/video/fbdev/core/fbmem.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 0da75c55660d..861bf8081619 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1117,6 +1117,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, if (!lock_fb_info(info)) return -ENODEV; fix = info->fix; + if (info->flags & FBINFO_HIDE_SMEM_START) + fix.smem_start = 0; unlock_fb_info(info); ret = copy_to_user(argp, &fix, sizeof(fix)) ? -EFAULT : 0; @@ -1327,6 +1329,8 @@ static int fb_get_fscreeninfo(struct fb_info *info, unsigned int cmd, if (!lock_fb_info(info)) return -ENODEV; fix = info->fix; + if (info->flags & FBINFO_HIDE_SMEM_START) + fix.smem_start = 0; unlock_fb_info(info); return do_fscreeninfo_to_user(&fix, compat_ptr(arg)); } |