From b61732f47316d45f27706db7812950145d3327b5 Mon Sep 17 00:00:00 2001 From: Deepanshu Kartikey Date: Wed, 23 Sep 2026 09:26:27 +0530 Subject: [PATCH] nfc: pn533: fix OOB read in pn533_acr122_is_rx_frame_valid() frame->ccid.datalen is read directly from the USB response frame and used, unchecked, as an index into frame->data[]. A malicious or malfunctioning device can set this field to an arbitrary value, causing the driver to read far outside the received buffer. Bound ccid.datalen against the maximum possible ACR122 frame size before using it. This replaces the existing datalen == 0 check, since datalen < 2 already covers that case and additionally rejects datalen == 1, which would still underflow the "datalen - 2" offset used below. Fixes: 9815c7cf22da ("NFC: pn533: Separate physical layer from the core implementation") Reported-by: syzbot+1853daab1a47603d4678@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1853daab1a47603d4678 Tested-by: syzbot+1853daab1a47603d4678@syzkaller.appspotmail.com Assisted-by: LLM Signed-off-by: Deepanshu Kartikey Link: https://patch.msgid.link/20260923035627.6210-1-kartikey406@gmail.com Signed-off-by: David Heidelberg --- drivers/nfc/pn533/usb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/nfc/pn533/usb.c b/drivers/nfc/pn533/usb.c index efb07f944fce..972eaac09e59 100644 --- a/drivers/nfc/pn533/usb.c +++ b/drivers/nfc/pn533/usb.c @@ -319,7 +319,9 @@ static bool pn533_acr122_is_rx_frame_valid(void *_frame, struct pn533 *dev) if (frame->ccid.type != 0x83) return false; - if (!frame->ccid.datalen) + if (frame->ccid.datalen < 2 || + frame->ccid.datalen > PN533_ACR122_FRAME_MAX_PAYLOAD_LEN + + PN533_ACR122_RX_FRAME_TAIL_LEN) return false; if (frame->data[frame->ccid.datalen - 2] == 0x63)