* [PATCH] ALSA: ump: do not touch legacy_rmidi before it exists
@ 2026-09-02 7:39 Qingyu Zhang
2026-09-02 9:11 ` Takashi Iwai
0 siblings, 1 reply; 2+ messages in thread
From: Qingyu Zhang @ 2026-09-02 7:39 UTC (permalink / raw)
To: perex, tiwai; +Cc: linux-kernel, linux-sound
snd_ump_parse_endpoint() sets ump->parsed on every exit, including
error, before the caller attaches the legacy rawmidi device.
ump_handle_ep_name_msg() then treats parsed as "legacy_rmidi is live"
and calls ump_legacy_set_rawmidi_name(), which snprintf()s into
ump->legacy_rmidi->name. If a UMP packet arrives in that window
(IRQ path from snd_ump_receive), legacy_rmidi is still NULL
(KASAN null-ptr-deref in snprintf).
Guard the legacy helpers. parsed only means endpoint info was
parsed, not that legacy_rmidi exists.
Fixes: 37e0e14128e0 ("ALSA: ump: Support UMP Endpoint and Function Block parsing")
Signed-off-by: Qingyu Zhang <usupergate@gmail.com>
---
diff --git a/sound/core/ump.c b/sound/core/ump.c
index d183c8a000bd..3d1a2ed3b476 100644
--- a/sound/core/ump.c
+++ b/sound/core/ump.c
@@ -1335,6 +1335,8 @@ static void update_legacy_names(struct snd_ump_endpoint *ump)
{
struct snd_rawmidi *rmidi = ump->legacy_rmidi;
+ if (!rmidi)
+ return;
update_legacy_substreams(ump, rmidi, SNDRV_RAWMIDI_STREAM_INPUT);
update_legacy_substreams(ump, rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT);
}
@@ -1343,6 +1345,8 @@ static void ump_legacy_set_rawmidi_name(struct snd_ump_endpoint *ump)
{
struct snd_rawmidi *rmidi = ump->legacy_rmidi;
+ if (!rmidi)
+ return;
snprintf(rmidi->name, sizeof(rmidi->name), "%.68s (MIDI 1.0)",
ump->core.name);
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ALSA: ump: do not touch legacy_rmidi before it exists
2026-09-02 7:39 [PATCH] ALSA: ump: do not touch legacy_rmidi before it exists Qingyu Zhang
@ 2026-09-02 9:11 ` Takashi Iwai
0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2026-09-02 9:11 UTC (permalink / raw)
To: Qingyu Zhang; +Cc: perex, tiwai, linux-kernel, linux-sound
On Wed, 02 Sep 2026 09:39:18 +0200,
Qingyu Zhang wrote:
>
> snd_ump_parse_endpoint() sets ump->parsed on every exit, including
> error, before the caller attaches the legacy rawmidi device.
> ump_handle_ep_name_msg() then treats parsed as "legacy_rmidi is live"
> and calls ump_legacy_set_rawmidi_name(), which snprintf()s into
> ump->legacy_rmidi->name. If a UMP packet arrives in that window
> (IRQ path from snd_ump_receive), legacy_rmidi is still NULL
> (KASAN null-ptr-deref in snprintf).
>
> Guard the legacy helpers. parsed only means endpoint info was
> parsed, not that legacy_rmidi exists.
>
> Fixes: 37e0e14128e0 ("ALSA: ump: Support UMP Endpoint and Function Block parsing")
> Signed-off-by: Qingyu Zhang <usupergate@gmail.com>
Applied now. Thanks.
Takashi
^ permalink raw reply [flat|nested] 2+ messages in thread
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