[PATCH 6.18 207/396] ALSA: ump: fix double free of out_cvts on rawmidi error

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Baul Lee <[email protected]>

commit 70c977815af0d997feb2d0c5d284d55689bf7051 upstream.

snd_ump_attach_legacy_rawmidi() allocates the legacy conversion array
ump->out_cvts and, on the snd_rawmidi_new() error path, frees it with
kfree() but leaves ump->out_cvts pointing at the freed memory.  When the
endpoint is later torn down, snd_ump_endpoint_free() frees ump->out_cvts
a second time, resulting in a double free.

The host snd-usb-audio driver attaches the legacy rawmidi for any USB
MIDI 2.0 (UMP) device, so a device that makes snd_rawmidi_new() fail
reaches this path on enumeration.

Clear ump->out_cvts after freeing it on the error path so it is not
freed again during teardown.

Discovered by XBOW, triaged by Baul Lee <[email protected]>

Fixes: 33cd7630782d ("ALSA: ump: Export MIDI1 / UMP conversion helpers")
Reported-by: Federico Kirschbaum <[email protected]>
Reported-by: Baul Lee <[email protected]>
Cc: [email protected]
Signed-off-by: Baul Lee <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 sound/core/ump.c |    1 +
 1 file changed, 1 insertion(+)

--- a/sound/core/ump.c
+++ b/sound/core/ump.c
@@ -1366,6 +1366,7 @@ int snd_ump_attach_legacy_rawmidi(struct
 			      &rmidi);
 	if (err < 0) {
 		kfree(ump->out_cvts);
+		ump->out_cvts = NULL;
 		return err;
 	}