Hi!
> [ Upstream commit feb689025fbb6f0aa6297d3ddf97de945ea4ad32 ]
>
> ALSA OSS sequencer calls the ioctl function indirectly via
> snd_seq_kernel_client_ctl(). While we already applied the protection
> against races between the normal ioctls and writes via the client's
> ioctl_mutex, this code path was left untouched. And this seems to be
> the cause of still remaining some rare UAF as spontaneously triggered
> by syzkaller.
>
> For the sake of robustness, wrap the ioctl_mutex also for the call via
> snd_seq_kernel_client_ctl(), too.
This is reverted with patch after the next one. Should simply this and
the revert be deleted from the queue?
Thanks,
Pavel
> diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
> index 38e7deab6384..b3280e81bfd1 100644
> --- a/sound/core/seq/seq_clientmgr.c
> +++ b/sound/core/seq/seq_clientmgr.c
> @@ -2343,14 +2343,19 @@ int snd_seq_kernel_client_ctl(int clientid, unsigned int cmd, void *arg)
> {
> const struct ioctl_handler *handler;
> struct snd_seq_client *client;
> + int err;
>
> client = clientptr(clientid);
> if (client == NULL)
> return -ENXIO;
>
> for (handler = ioctl_handlers; handler->cmd > 0; ++handler) {
> - if (handler->cmd == cmd)
> - return handler->func(client, arg);
> + if (handler->cmd == cmd) {
> + mutex_lock(&client->ioctl_mutex);
> + err = handler->func(client, arg);
> + mutex_unlock(&client->ioctl_mutex);
> + return err;
> + }
> }
>
> pr_debug("ALSA: seq unknown ioctl() 0x%x (type='%c', number=0x%02x)\n",
--
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