[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <lsq.1565469607.608627100@decadent.org.uk>
Date: Sat, 10 Aug 2019 21:40:07 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
"Gustavo A. R. Silva" <gustavo@...eddedor.com>,
"Takashi Iwai" <tiwai@...e.de>
Subject: [PATCH 3.16 037/157] ALSA: seq: oss: Fix Spectre v1 vulnerability
3.16.72-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
commit c709f14f0616482b67f9fbcb965e1493a03ff30b upstream.
dev 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/seq/oss/seq_oss_synth.c:626 snd_seq_oss_synth_make_info() warn: potential spectre issue 'dp->synths' [w] (local cap)
Fix this by sanitizing dev before using it to index dp->synths.
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/
Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
sound/core/seq/oss/seq_oss_synth.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/sound/core/seq/oss/seq_oss_synth.c
+++ b/sound/core/seq/oss/seq_oss_synth.c
@@ -617,13 +617,14 @@ int
snd_seq_oss_synth_make_info(struct seq_oss_devinfo *dp, int dev, struct synth_info *inf)
{
struct seq_oss_synth *rec;
+ struct seq_oss_synthinfo *info = get_synthinfo_nospec(dp, dev);
- if (dev < 0 || dev >= dp->max_synthdev)
+ if (!info)
return -ENXIO;
- if (dp->synths[dev].is_midi) {
+ if (info->is_midi) {
struct midi_info minf;
- snd_seq_oss_midi_make_info(dp, dp->synths[dev].midi_mapped, &minf);
+ snd_seq_oss_midi_make_info(dp, info->midi_mapped, &minf);
inf->synth_type = SYNTH_TYPE_MIDI;
inf->synth_subtype = 0;
inf->nr_voices = 16;
Powered by blists - more mailing lists