Patch "ALSA: usx2y: Don't call free_pages_exact() with NULL address" has been added to the 5.13-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    ALSA: usx2y: Don't call free_pages_exact() with NULL address

to the 5.13-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-usx2y-don-t-call-free_pages_exact-with-null-add.patch
and it can be found in the queue-5.13 subdirectory.

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



commit bf62c8838e881d6fcf583a3546546026e3f6d313
Author: Takashi Iwai <tiwai@xxxxxxx>
Date:   Mon May 17 15:15:43 2021 +0200

    ALSA: usx2y: Don't call free_pages_exact() with NULL address
    
    [ Upstream commit cae0cf651adccee2c3f376e78f30fbd788d0829f ]
    
    Unlike some other functions, we can't pass NULL pointer to
    free_pages_exact().  Add a proper NULL check for avoiding possible
    Oops.
    
    Link: https://lore.kernel.org/r/20210517131545.27252-10-tiwai@xxxxxxx
    Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/sound/usb/usx2y/usb_stream.c b/sound/usb/usx2y/usb_stream.c
index 091c071b270a..cff684942c4f 100644
--- a/sound/usb/usx2y/usb_stream.c
+++ b/sound/usb/usx2y/usb_stream.c
@@ -142,8 +142,11 @@ void usb_stream_free(struct usb_stream_kernel *sk)
 	if (!s)
 		return;
 
-	free_pages_exact(sk->write_page, s->write_size);
-	sk->write_page = NULL;
+	if (sk->write_page) {
+		free_pages_exact(sk->write_page, s->write_size);
+		sk->write_page = NULL;
+	}
+
 	free_pages_exact(s, s->read_size);
 	sk->s = NULL;
 }