6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai <tiwai@xxxxxxx> commit 0179488ca992d79908b8e26b9213f1554fc5bacc upstream. OSS sequencer handles the SysEx messages split in 6 bytes packets, and ALSA sequencer OSS layer tries to combine those. It stores the data in the internal buffer and this access is racy as of now, which may lead to the out-of-bounds access. As a temporary band-aid fix, introduce a mutex for serializing the process of the SysEx message packets. Reported-by: Kun Hu <huk23@xxxxxxxxxxxxxx> Closes: https://lore.kernel.org/2B7E93E4-B13A-4AE4-8E87-306A8EE9BBB7@xxxxxxxxxxxxxx Cc: <stable@xxxxxxxxxxxxxxx> Link: https://patch.msgid.link/20241230110543.32454-1-tiwai@xxxxxxx Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- sound/core/seq/oss/seq_oss_synth.c | 2 ++ 1 file changed, 2 insertions(+) --- a/sound/core/seq/oss/seq_oss_synth.c +++ b/sound/core/seq/oss/seq_oss_synth.c @@ -66,6 +66,7 @@ static struct seq_oss_synth midi_synth_d }; static DEFINE_SPINLOCK(register_lock); +static DEFINE_MUTEX(sysex_mutex); /* * prototypes @@ -497,6 +498,7 @@ snd_seq_oss_synth_sysex(struct seq_oss_d if (!info) return -ENXIO; + guard(mutex)(&sysex_mutex); sysex = info->sysex; if (sysex == NULL) { sysex = kzalloc(sizeof(*sysex), GFP_KERNEL);
