| From 5ae4f61f012a097df93de2285070ec8e34716d29 Mon Sep 17 00:00:00 2001 |
| From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> |
| Date: Tue, 18 Dec 2018 11:52:16 -0600 |
| Subject: ALSA: emu10k1: Fix potential Spectre v1 vulnerabilities |
| |
| From: Gustavo A. R. Silva <gustavo@embeddedor.com> |
| |
| commit 5ae4f61f012a097df93de2285070ec8e34716d29 upstream. |
| |
| ipcm->substream 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/pci/emu10k1/emufx.c:1031 snd_emu10k1_ipcm_poke() warn: potential spectre issue 'emu->fx8010.pcm' [r] (local cap) |
| sound/pci/emu10k1/emufx.c:1075 snd_emu10k1_ipcm_peek() warn: potential spectre issue 'emu->fx8010.pcm' [r] (local cap) |
| |
| Fix this by sanitizing ipcm->substream before using it to index emu->fx8010.pcm |
| |
| 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://marc.info/?l=linux-kernel&m=152449131114778&w=2 |
| |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> |
| Signed-off-by: Takashi Iwai <tiwai@suse.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| sound/pci/emu10k1/emufx.c | 5 +++++ |
| 1 file changed, 5 insertions(+) |
| |
| --- a/sound/pci/emu10k1/emufx.c |
| +++ b/sound/pci/emu10k1/emufx.c |
| @@ -36,6 +36,7 @@ |
| #include <linux/init.h> |
| #include <linux/mutex.h> |
| #include <linux/moduleparam.h> |
| +#include <linux/nospec.h> |
| |
| #include <sound/core.h> |
| #include <sound/tlv.h> |
| @@ -1000,6 +1001,8 @@ static int snd_emu10k1_ipcm_poke(struct |
| |
| if (ipcm->substream >= EMU10K1_FX8010_PCM_COUNT) |
| return -EINVAL; |
| + ipcm->substream = array_index_nospec(ipcm->substream, |
| + EMU10K1_FX8010_PCM_COUNT); |
| if (ipcm->channels > 32) |
| return -EINVAL; |
| pcm = &emu->fx8010.pcm[ipcm->substream]; |
| @@ -1046,6 +1049,8 @@ static int snd_emu10k1_ipcm_peek(struct |
| |
| if (ipcm->substream >= EMU10K1_FX8010_PCM_COUNT) |
| return -EINVAL; |
| + ipcm->substream = array_index_nospec(ipcm->substream, |
| + EMU10K1_FX8010_PCM_COUNT); |
| pcm = &emu->fx8010.pcm[ipcm->substream]; |
| mutex_lock(&emu->fx8010.lock); |
| spin_lock_irq(&emu->reg_lock); |