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ALSA: rawmidi: Fix NULL dereference at proc read

Message ID 20230916060725.11726-1-tiwai@suse.de (mailing list archive)
State New, archived
Headers show
Series ALSA: rawmidi: Fix NULL dereference at proc read | expand

Commit Message

Takashi Iwai Sept. 16, 2023, 6:07 a.m. UTC
At the implementation of the optional proc fs in rawmidi, I forgot
that rmidi->ops itself is optional and can be NULL.
Add the proper NULL check for avoiding the Oops.

Fixes: fa030f666d24 ("ALSA: ump: Additional proc output")
Reported-and-tested-by: Mark Hills <mark@xwax.org>
Closes: https://lore.kernel.org/r/ef9118c3-a2eb-d0ff-1efa-cc5fb6416bde@xwax.org
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/rawmidi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index ba06484ac4aa..1431cb997808 100644
--- 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) {