On Fri, 15 Sep 2023, Takashi Iwai wrote:
> On Fri, 15 Sep 2023 19:30:51 +0200, Takashi Iwai wrote:
> >
> > On Fri, 15 Sep 2023 18:04:35 +0200, Mark Hills wrote:
[...]
> > > I upgraded from 6.1.0 to 6.5.3 and Reaper now crashes or hangs on startup
> > > with the trace below in dmesg.
> > >
> > > The newer kernel already includes a fix very similar to below, so I think
> > > an issue remains.
> > >
> > > I did not dig deeper than capturing information and finding this related
> > > thread.
> > (snip)
> > > [ 72.601440] BUG: kernel NULL pointer dereference, address: 0000000000000020
> > (snip)
> > > [ 72.601455] RIP: 0010:snd_rawmidi_proc_info_read+0x35/0x220 [snd_rawmidi]
> > (snip)
> > > [ 72.601477] Call Trace:
> > > [ 72.601478] <TASK>
> > > [ 72.601479] ? __die+0x1b/0x60
> > > [ 72.601482] ? page_fault_oops+0x154/0x420
> > > [ 72.601485] ? mas_update_gap.part.0+0xac/0x1f0
> > > [ 72.601488] ? sched_clock_cpu+0xb/0x190
> > > [ 72.601491] ? __smp_call_single_queue+0x2f/0x50
> > > [ 72.601493] ? exc_page_fault+0x37a/0x560
> > > [ 72.601495] ? seq_open+0x4b/0x70
> > > [ 72.601497] ? asm_exc_page_fault+0x22/0x30
> > > [ 72.601501] ? snd_rawmidi_proc_info_read+0x35/0x220 [snd_rawmidi]
> > > [ 72.601505] snd_info_seq_show+0x21/0x40 [snd]
> > > [ 72.601511] seq_read_iter+0x105/0x4a0
> > > [ 72.601514] seq_read+0x9e/0xd0
> > > [ 72.601516] proc_reg_read+0x50/0xa0
> > > [ 72.601518] vfs_read+0xa4/0x300
> > > [ 72.601521] ? __do_sys_newfstatat+0x35/0x60
> > > [ 72.601524] ksys_read+0x5a/0xe0
> > > [ 72.601526] do_syscall_64+0x38/0x90
> > > [ 72.601528] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> >
> > It must be a completely different bug. It comes from the proc fs
> > read, not the read over sequencer device itself.
>
> Does the change below fix the problem?
It does! At least it passes my initial test. Reaper starts up now.
> -- 8< --
> --- a/sound/core/rawmidi.c
> +++ b/sound/core/rawmidi.c
> @@ -1770,7 +1770,7 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
> if (IS_ENABLED(CONFIG_SND_UMP))
> snd_iprintf(buffer, "Type: %s\n",
> rawmidi_is_ump(rmidi) ? "UMP" : "Legacy");
> - if (rmidi->ops->proc_read)
> + if (rmidi->ops && rmidi->ops->proc_read)
> rmidi->ops->proc_read(entry, buffer);
> mutex_lock(&rmidi->open_mutex);
> if (rmidi->info_flags & SNDRV_RAWMIDI_INFO_OUTPUT) {
>
>
>
--
Mark
