Patch "ALSA: core: Fix unexpected error at replacing user TLV" has been added to the 3.18-stable tree

Patch "ALSA: core: Fix unexpected error at replacing user TLV" has been added to the 3.18-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ALSA: core: Fix unexpected error at replacing user TLV

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     alsa-core-fix-unexpected-error-at-replacing-user-tlv.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 88c54cdf61f508ebcf8da2d819f5dfc03e954d1d Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 22 Aug 2017 08:15:13 +0200
Subject: ALSA: core: Fix unexpected error at replacing user TLV

From: Takashi Iwai <tiwai@suse.de>

commit 88c54cdf61f508ebcf8da2d819f5dfc03e954d1d upstream.

When user tries to replace the user-defined control TLV, the kernel
checks the change of its content via memcmp().  The problem is that
the kernel passes the return value from memcmp() as is.  memcmp()
gives a non-zero negative value depending on the comparison result,
and this shall be recognized as an error code.

The patch covers that corner-case, return 1 properly for the changed
TLV.

Fixes: 8aa9b586e420 ("[ALSA] Control API - more robust TLV implementation")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 sound/core/control.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1087,7 +1087,7 @@ static int snd_ctl_elem_user_tlv(struct
 		mutex_lock(&ue->card->user_ctl_lock);
 		change = ue->tlv_data_size != size;
 		if (!change)
-			change = memcmp(ue->tlv_data, new_data, size);
+			change = memcmp(ue->tlv_data, new_data, size) != 0;
 		kfree(ue->tlv_data);
 		ue->tlv_data = new_data;
 		ue->tlv_data_size = size;


Patches currently in stable-queue which might be from tiwai@suse.de are

queue-3.18/alsa-hda-add-stereo-mic-quirk-for-lenovo-g50-70-17aa-3978.patch
queue-3.18/alsa-core-fix-unexpected-error-at-replacing-user-tlv.patch