Re: [BUG] ALSA: seq: a possible sleep-in-atomic-context bug in snd_virmidi_dev_receive_event()

[Greg KH]

On Tue, Dec 17, 2019 at 09:24:21PM +0800, Jia-Ju Bai wrote:
> The driver may sleep while holding a read lock.
> The function call path (from bottom to top) in Linux 4.19 is:
> 
> sound/core/seq/seq_memory.c, 96:
>     copy_from_user in snd_seq_dump_var_event
> sound/core/seq/seq_virmidi.c, 97:
>     snd_seq_dump_var_event in snd_virmidi_dev_receive_event
> sound/core/seq/seq_virmidi.c, 88:
>     _raw_read_lock in snd_virmidi_dev_receive_event
> 
> copy_from_user() can sleep at runtime.
> 
> I am not sure how to properly fix this possible bug, so I only report it.
> 
> This bug is found by a static analysis tool STCheck written by myself.

Patches for this is usually best :)