ALSA: hdspm: Hardening for potential Spectre v1

commit 10513142a7 upstream.

As recently Smatch suggested, a couple of places in HDSP MADI driver
may expand the array directly from the user-space value with
speculation:
  sound/pci/rme9652/hdspm.c:5717 snd_hdspm_channel_info() warn: potential spectre issue 'hdspm->channel_map_out' (local cap)
  sound/pci/rme9652/hdspm.c:5734 snd_hdspm_channel_info() warn: potential spectre issue 'hdspm->channel_map_in' (local cap)

This patch puts array_index_nospec() for hardening against them.

BugLink: https://marc.info/?l=linux-kernel&m=152411496503418&w=2
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Takashi Iwai 2018-04-24 08:03:14 +02:00 • committed by Ben Hutchings
commit 01d4acf218