From: Gustavo A. R. Silva Date: Wed, 20 Mar 2019 23:42:01 +0000 (-0500) Subject: ALSA: seq: oss: Fix Spectre v1 vulnerability X-Git-Tag: Ubuntu-4.15.0-49.53~14 X-Git-Url: https://git.proxmox.com/?p=mirror_ubuntu-bionic-kernel.git;a=commitdiff_plain;h=77151e5755fc89cd2034b79c924d530d7d9c0cdd ALSA: seq: oss: Fix Spectre v1 vulnerability 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/ Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva Signed-off-by: Takashi Iwai CVE-2017-5753 (cherry picked from commit c709f14f0616482b67f9fbcb965e1493a03ff30b) Signed-off-by: Juerg Haefliger Acked-by: Stefan Bader Acked-by: Kleber Sacilotto de Souza Signed-off-by: Stefan Bader --- diff --git a/sound/core/seq/oss/seq_oss_synth.c b/sound/core/seq/oss/seq_oss_synth.c index 278ebb993122..c93945917235 100644 --- 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;