Commit 70b4db7d authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: usb-audio: Use the right limit for PCM OOB check 

The recent fix commit for addressing the OOB access of PCM URB data
buffer caused a regression on Behringer UMC2020HD device, resulting in
choppy sound.  The fix used ep->max_urb_frames for the upper limit
check, and this is no right value to be referred.

Use the actual buffer size (ctx->buffer_size) as the upper limit
instead, which also avoids the regression on the device above.

Fixes: ef5749ef ("ALSA: usb-audio: Prevent excessive number of frames")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=220997
Link: https://patch.msgid.link/20260121082025.718748-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 930e6975

sound/usb/pcm.c

+2 −1
Original line number Diff line number Diff line
@@ -1553,7 +1553,8 @@ static int prepare_playback_urb(struct snd_usb_substream *subs, 


		for (i = 0; i < ctx->packets; i++) {

			counts = snd_usb_endpoint_next_packet_size(ep, ctx, i, avail);

			if (counts < 0 || frames + counts >= ep->max_urb_frames)

			if (counts < 0 ||

			    (frames + counts) * stride > ctx->buffer_size)

				break;

			/* set up descriptor */

			urb->iso_frame_desc[i].offset = frames * stride;