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authorTakashi Iwai <tiwai@suse.de>2017-10-09 17:05:35 +0200
committerTakashi Iwai <tiwai@suse.de>2017-10-10 13:45:13 +0200
commit19b592dae895aad10b84246b0e12caad04e9eb0d (patch)
tree7e26bb0aaebe09cdc7b7dc6d0c42b8b2bfef23df
parenta6aa6cdcecfc0eb8a6fe634535384b4a63f38258 (diff)
ALSA: seq: Add sanity check for user-space pointer delivery
The sequencer event may contain a user-space pointer with its SNDRV_SEQ_EXT_USRPTR bit, and we assure that its delivery is limited with non-atomic mode. Otherwise the copy_from_user() may hit the fault and cause a problem. Although the core code doesn't set such a flag (only set at snd_seq_write()), any wild driver may set it mistakenly and lead to an unexpected crash. This patch adds a sanity check of such events at the delivery core code to filter out the invalid invocation in the atomic mode. Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/core/seq/seq_clientmgr.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
index ea2d0ae85bd3..f2343f63ba26 100644
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -802,6 +802,10 @@ static int snd_seq_deliver_event(struct snd_seq_client *client, struct snd_seq_e
return -EMLINK;
}
+ if (snd_seq_ev_is_variable(event) &&
+ snd_BUG_ON(atomic && (event->data.ext.len & SNDRV_SEQ_EXT_USRPTR)))
+ return -EINVAL;
+
if (event->queue == SNDRV_SEQ_ADDRESS_SUBSCRIBERS ||
event->dest.client == SNDRV_SEQ_ADDRESS_SUBSCRIBERS)
result = deliver_to_subscribers(client, event, atomic, hop);