From: Takashi Iwai Date: Mon, 9 Oct 2017 15:05:35 +0000 (+0200) Subject: ALSA: seq: Add sanity check for user-space pointer delivery X-Git-Tag: v5.15~10022^2~2^2~27 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=19b592dae895aad10b84246b0e12caad04e9eb0d;p=mirror_ubuntu-kernels.git 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 --- 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);