From: Berk Cem Goksel Date: Sun, 29 Mar 2026 13:38:25 +0000 (+0300) Subject: ALSA: caiaq: fix stack out-of-bounds read in init_card X-Git-Tag: v7.0-rc7~30^2~10 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=45424e871abf2a152e247a9cff78359f18dd95c0;p=thirdparty%2Fkernel%2Flinux.git ALSA: caiaq: fix stack out-of-bounds read in init_card The loop creates a whitespace-stripped copy of the card shortname where `len < sizeof(card->id)` is used for the bounds check. Since sizeof(card->id) is 16 and the local id buffer is also 16 bytes, writing 16 non-space characters fills the entire buffer, overwriting the terminating nullbyte. When this non-null-terminated string is later passed to snd_card_set_id() -> copy_valid_id_string(), the function scans forward with `while (*nid && ...)` and reads past the end of the stack buffer, reading the contents of the stack. A USB device with a product name containing many non-ASCII, non-space characters (e.g. multibyte UTF-8) will reliably trigger this as follows: BUG: KASAN: stack-out-of-bounds in copy_valid_id_string sound/core/init.c:696 [inline] BUG: KASAN: stack-out-of-bounds in snd_card_set_id_no_lock+0x698/0x74c sound/core/init.c:718 The off-by-one has been present since commit bafeee5b1f8d ("ALSA: snd_usb_caiaq: give better shortname") from June 2009 (v2.6.31-rc1), which first introduced this whitespace-stripping loop. The original code never accounted for the null terminator when bounding the copy. Fix this by changing the loop bound to `sizeof(card->id) - 1`, ensuring at least one byte remains as the null terminator. Fixes: bafeee5b1f8d ("ALSA: snd_usb_caiaq: give better shortname") Cc: stable@vger.kernel.org Cc: Andrey Konovalov Reported-by: Berk Cem Goksel Signed-off-by: Berk Cem Goksel Link: https://patch.msgid.link/20260329133825.581585-1-berkcgoksel@gmail.com Signed-off-by: Takashi Iwai --- diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c index dfd820483849..3a71bab8a477 100644 --- a/sound/usb/caiaq/device.c +++ b/sound/usb/caiaq/device.c @@ -488,7 +488,7 @@ static int init_card(struct snd_usb_caiaqdev *cdev) memset(id, 0, sizeof(id)); for (c = card->shortname, len = 0; - *c && len < sizeof(card->id); c++) + *c && len < sizeof(card->id) - 1; c++) if (*c != ' ') id[len++] = *c;