On Tue, 12 Oct 2021 17:15:56 +0200, Pierre-Louis Bossart wrote:
In either way, the new_ptr has to be validated beforehand that it's within 0..boundary-1. (old_ptr is assumed to be valid.)
In the 3 of the calls to pcm_lib_apply_appl_ptr(), the check is done already prior to calling that function if (appl_ptr >= runtime->boundary) appl_ptr -= runtime->boundary; err = pcm_lib_apply_appl_ptr(substream, appl_ptr);
it's rather unclear to me why the same check is not done for sync_ptr, e.g.
if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, sync_ptr.c.control.appl_ptr);
if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, scontrol.appl_ptr);
Should I add a check there, or add a check inside of pcm_lib_apply_appl_ptr() which would be a duplicate in the majority of cases?
I guess adding in pcm_lib_appl_appl_ptr() would be easier and safer. There is even one more place that is calling pcm_lib_apply_appl_ptr() in the very latest commit (a fix for a buggy 32bit compat ioctl).
thanks,
Takashi