From 861111a14740e12c36d363e9830f8daa734279c9 Mon Sep 17 00:00:00 2001 From: Tristan Madani Date: Fri, 4 Sep 2026 20:58:25 +0000 Subject: [PATCH] ALSA: usbusx2y: fix in04_last array size mismatch with in04_buf The in04_last array in struct usx2ydev is declared as char[24], but in04_buf is allocated as sizeof(struct us428_ctls) which is 21 bytes. In i_usx2y_in04_int(), when ctl_snapshot_last == -2 (initialization path): memcpy(usx2y->in04_last, usx2y->in04_buf, sizeof(usx2y->in04_last)); This copies 24 bytes from a 21-byte slab allocation, reading 3 bytes past the end of the source object. Introduce a USX2Y_IN04_SIZE constant defined as sizeof(struct us428_ctls) and use it consistently for the in04_last array, the in04_buf allocation, the URB transfer length, and the comparison loop, replacing the bare 24 and 21 literals throughout. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Tristan Madani Link: https://patch.msgid.link/20260904205826.4071119-1-tristmd@gmail.com Signed-off-by: Takashi Iwai --- sound/usb/usx2y/usbusx2y.c | 6 +++--- sound/usb/usx2y/usbusx2y.h | 4 +++- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/sound/usb/usx2y/usbusx2y.c b/sound/usb/usx2y/usbusx2y.c index 4190227c5a2a..200b708aacd6 100644 --- a/sound/usb/usx2y/usbusx2y.c +++ b/sound/usb/usx2y/usbusx2y.c @@ -196,7 +196,7 @@ static void i_usx2y_in04_int(struct urb *urb) memcpy(usx2y->in04_last, usx2y->in04_buf, sizeof(usx2y->in04_last)); us428ctls->ctl_snapshot_last = -1; } else { - for (i = 0; i < 21; i++) { + for (i = 0; i < USX2Y_IN04_SIZE; i++) { if (usx2y->in04_last[i] != ((char *)usx2y->in04_buf)[i]) { if (diff < 0) diff = i; @@ -305,7 +305,7 @@ int usx2y_in04_init(struct usx2ydev *usx2y) goto error; } - usx2y->in04_buf = kmalloc(21, GFP_KERNEL); + usx2y->in04_buf = kmalloc(USX2Y_IN04_SIZE, GFP_KERNEL); if (!usx2y->in04_buf) { err = -ENOMEM; goto error; @@ -313,7 +313,7 @@ int usx2y_in04_init(struct usx2ydev *usx2y) init_waitqueue_head(&usx2y->in04_wait_queue); usb_fill_int_urb(usx2y->in04_urb, usx2y->dev, usb_rcvintpipe(usx2y->dev, 0x4), - usx2y->in04_buf, 21, + usx2y->in04_buf, USX2Y_IN04_SIZE, i_usx2y_in04_int, usx2y, 10); if (usb_urb_ep_type_check(usx2y->in04_urb)) { diff --git a/sound/usb/usx2y/usbusx2y.h b/sound/usb/usx2y/usbusx2y.h index 6a76d04bf1c7..7b6deed17d4b 100644 --- a/sound/usb/usx2y/usbusx2y.h +++ b/sound/usb/usx2y/usbusx2y.h @@ -5,6 +5,8 @@ #include "../midi.h" #include "usbus428ctldefs.h" +#define USX2Y_IN04_SIZE sizeof(struct us428_ctls) + #define NRURBS 2 /* Default value used for nr of packs per urb. @@ -55,7 +57,7 @@ struct usx2ydev { int stride; struct urb *in04_urb; void *in04_buf; - char in04_last[24]; + char in04_last[USX2Y_IN04_SIZE]; unsigned int in04_int_calls; struct snd_usx2y_urb_seq *us04; wait_queue_head_t in04_wait_queue;