From f3acd269c842c035e05fb62951a2fec5a4d6bfce Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Wed, 20 Mar 2019 16:15:24 -0500 Subject: ALSA: rawmidi: Fix potential Spectre v1 vulnerability commit 2b1d9c8f87235f593826b9cf46ec10247741fff9 upstream. info->stream is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: sound/core/rawmidi.c:604 __snd_rawmidi_info_select() warn: potential spectre issue 'rmidi->streams' [r] (local cap) Fix this by sanitizing info->stream before using it to index rmidi->streams. Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://lore.kernel.org/lkml/20180423164740.GY17484@dhcp22.suse.cz/ Change-Id: I2c8b93b82ad4374027a03dc4c73fdf74eee696e6 Signed-off-by: Gustavo A. R. Silva Signed-off-by: Takashi Iwai [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- sound/core/rawmidi.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c index 930891887..370d44235 100644 --- a/sound/core/rawmidi.c +++ b/sound/core/rawmidi.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include #include @@ -589,6 +590,7 @@ int snd_rawmidi_info_select(struct snd_card *card, struct snd_rawmidi_info *info return -ENXIO; if (info->stream < 0 || info->stream > 1) return -EINVAL; + info->stream = array_index_nospec(info->stream, 2); pstr = &rmidi->streams[info->stream]; if (pstr->substream_count == 0) return -ENOENT; -- cgit v1.2.3