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> struct drm_syncobj_create arg1; > ioctl(fd, DRM_IOCTL_SYNCOBJ_CREATE, &arg1); > struct drm_syncobj_handle arg2; > memset(&arg2, 1, sizeof(arg2)); // simulate dirty stack > arg2.handle = arg1.handle; > arg2.flags = 0; > arg2.fd = 0; > arg2.pad = 0; > // arg2.point = 0; // userspace is required to set point to 0 > ioctl(fd, DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD, &arg2); > } > > The last ioctl returns EINVAL because args->point is not 0. However, > userspace developed against older kernel versions is not aware of the > new point field and might therefore not initialize it. > > The correct check would be > > if (args->flags & DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_TIMELINE) > return -EINVAL; > > However, there might already be userspace that relies on this not > returning an error as long as point == 0. Therefore use the more lenient > check. > > Fixes: c2d3a7300695 ("drm/syncobj: Extend EXPORT_SYNC_FILE for timeline syncobjs") > Signed-off-by: Julian Orth Good catch, Reviewed-by: Christian König As long as nobody objects I'm going to push this to drm-misc-fixes later today. Thanks, Christian. > --- > This patch fixes a regression that would cause conversions between > syncobj handles and fds to fail if userspace did not initialize a > recently-added field to 0. > --- > drivers/gpu/drm/drm_syncobj.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c > index 250734dee928..49eccb43ce63 100644 > --- a/drivers/gpu/drm/drm_syncobj.c > +++ b/drivers/gpu/drm/drm_syncobj.c > @@ -875,7 +875,7 @@ drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data, > return drm_syncobj_export_sync_file(file_private, args->handle, > point, &args->fd); > > - if (args->point) > + if (point) > return -EINVAL; > > return drm_syncobj_handle_to_fd(file_private, args->handle, > @@ -909,7 +909,7 @@ drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data, > args->handle, > point); > > - if (args->point) > + if (point) > return -EINVAL; > > return drm_syncobj_fd_to_handle(file_private, args->fd, > > --- > base-commit: eb71ab2bf72260054677e348498ba995a057c463 > change-id: 20260301-point-4305b6417f55 > > Best regards, > -- > Julian Orth >