From 1be2143fb7b19e247f7c4aa1097f85fe92c132bf Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 26 Sep 2022 15:55:49 +0200 Subject: [PATCH] ALSA: pcm: Make mmap status read-only The mmap status record should be read-only. Modifying it from user-space may screw up things unexpectedly, so let's clear the write bits at exposing it. Note that alsa-lib and other known user-space apps access the mmapped status only as read-only, hence this change shouldn't break the existing applications. Reviewed-by: Jaroslav Kysela Link: https://lore.kernel.org/r/20220926135558.26580-3-tiwai@suse.de Signed-off-by: Takashi Iwai --- sound/core/pcm_native.c | 1 + 1 file changed, 1 insertion(+) diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index d9485b1ab719..33769ca78cc8 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3668,6 +3668,7 @@ static int snd_pcm_mmap_status(struct snd_pcm_substream *substream, struct file area->vm_ops = &snd_pcm_vm_ops_status; area->vm_private_data = substream; area->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; + area->vm_flags &= ~(VM_WRITE | VM_MAYWRITE); return 0; }