Commit 0179488c authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: seq: oss: Fix races at processing SysEx messages 



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: default avatarKun Hu <huk23@m.fudan.edu.cn>
Closes: https://lore.kernel.org/2B7E93E4-B13A-4AE4-8E87-306A8EE9BBB7@m.fudan.edu.cn
Cc: <stable@vger.kernel.org>
Link: https://patch.msgid.link/20241230110543.32454-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 7439b395

sound/core/seq/oss/seq_oss_synth.c

+2 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ static struct seq_oss_synth midi_synth_dev = { 
};



static DEFINE_SPINLOCK(register_lock);

static DEFINE_MUTEX(sysex_mutex);



/*

 * prototypes
@@ -497,6 +498,7 @@ snd_seq_oss_synth_sysex(struct seq_oss_devinfo *dp, int dev, unsigned char *buf, 
	if (!info)

		return -ENXIO;



	guard(mutex)(&sysex_mutex);

	sysex = info->sysex;

	if (sysex == NULL) {

		sysex = kzalloc(sizeof(*sysex), GFP_KERNEL);