From: Takashi Iwai Date: Mon, 30 Dec 2024 11:05:35 +0000 (+0100) Subject: ALSA: seq: oss: Fix races at processing SysEx messages X-Git-Tag: v6.13-rc6~13^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0179488ca992d79908b8e26b9213f1554fc5bacc;p=thirdparty%2Flinux.git 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: Kun Hu Closes: https://lore.kernel.org/2B7E93E4-B13A-4AE4-8E87-306A8EE9BBB7@m.fudan.edu.cn Cc: Link: https://patch.msgid.link/20241230110543.32454-1-tiwai@suse.de Signed-off-by: Takashi Iwai --- diff --git a/sound/core/seq/oss/seq_oss_synth.c b/sound/core/seq/oss/seq_oss_synth.c index e3394919daa09..51ee4c00a8431 100644 --- 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_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);