header->number and i are 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/isa/wavefront/wavefront_synth.c:792 wavefront_send_patch() warn: potential spectre issue 'dev->patch_status' [w] (local cap) sound/isa/wavefront/wavefront_synth.c:819 wavefront_send_program() warn: potential spectre issue 'dev->prog_status' [w] (local cap) sound/isa/wavefront/wavefront_synth.c:1197 wavefront_send_alias() warn: potential spectre issue 'dev->sample_status' [w] sound/isa/wavefront/wavefront_synth.c:1248 wavefront_send_multisample() warn: potential spectre issue 'dev->sample_status' [w] sound/isa/wavefront/wavefront_synth.c:1548 wavefront_synth_control() warn: potential spectre issue 'dev->sample_status' [r] (local cap) Fix this by sanitizing header->number and i before using them to index dev->patch_status, dev->prog_status, dev->sample_status. 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@xxxxxxxxxxxxxx/ Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> --- sound/isa/wavefront/wavefront_synth.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/sound/isa/wavefront/wavefront_synth.c b/sound/isa/wavefront/wavefront_synth.c index 0b1e4b34b299..a78e125dfdf9 100644 --- a/sound/isa/wavefront/wavefront_synth.c +++ b/sound/isa/wavefront/wavefront_synth.c @@ -31,6 +31,7 @@ #include <linux/moduleparam.h> #include <linux/slab.h> #include <linux/module.h> +#include <linux/nospec.h> #include <sound/core.h> #include <sound/snd_wavefront.h> #include <sound/initval.h> @@ -788,6 +789,8 @@ wavefront_send_patch (snd_wavefront_t *dev, wavefront_patch_info *header) if (header->number >= ARRAY_SIZE(dev->patch_status)) return -EINVAL; + header->number = array_index_nospec(header->number, + ARRAY_SIZE(dev->patch_status)); dev->patch_status[header->number] |= WF_SLOT_FILLED; @@ -815,6 +818,8 @@ wavefront_send_program (snd_wavefront_t *dev, wavefront_patch_info *header) if (header->number >= ARRAY_SIZE(dev->prog_status)) return -EINVAL; + header->number = array_index_nospec(header->number, + ARRAY_SIZE(dev->prog_status)); dev->prog_status[header->number] = WF_SLOT_USED; @@ -1194,6 +1199,11 @@ wavefront_send_alias (snd_wavefront_t *dev, wavefront_patch_info *header) return -EIO; } + if (header->number >= ARRAY_SIZE(dev->sample_status)) + return -EINVAL; + header->number = array_index_nospec(header->number, + ARRAY_SIZE(dev->sample_status)); + dev->sample_status[header->number] = (WF_SLOT_FILLED|WF_ST_ALIAS); return (0); @@ -1245,6 +1255,12 @@ wavefront_send_multisample (snd_wavefront_t *dev, wavefront_patch_info *header) return -EIO; } + if (header->number >= ARRAY_SIZE(dev->sample_status)) { + kfree(msample_hdr); + return -EINVAL; + } + header->number = array_index_nospec(header->number, + ARRAY_SIZE(dev->sample_status)); dev->sample_status[header->number] = (WF_SLOT_FILLED|WF_ST_MULTISAMPLE); kfree(msample_hdr); @@ -1545,6 +1561,7 @@ wavefront_synth_control (snd_wavefront_card_t *acard, wc->status = EINVAL; return -EINVAL; } + i = array_index_nospec(i, WF_MAX_SAMPLE); wc->rbuf[0] = dev->sample_status[i]; wc->status = 0; return 0; -- 2.21.0 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
