5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Deepanshu Kartikey [ Upstream commit b61732f47316d45f27706db7812950145d3327b5 ] 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 Signed-off-by: Sasha Levin --- 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 3ba6b387406c0..7fffd2c95864a 100644 --- a/drivers/nfc/pn533/usb.c +++ b/drivers/nfc/pn533/usb.c @@ -320,7 +320,9 @@ 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) -- 2.53.0