From: Maoyi Xie Date: Mon, 22 Jun 2026 08:01:57 +0000 (+0800) Subject: net: usb: kalmia: bound RX frame length in kalmia_rx_fixup() X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=47b6bcef6e679593d2e86e04ee72c46a4e2f7139;p=thirdparty%2Fkernel%2Fstable.git net: usb: kalmia: bound RX frame length in kalmia_rx_fixup() kalmia_rx_fixup() computes usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH) as a u16, guarded only by a pre-loop check that skb->len is at least KALMIA_HEADER_LENGTH, which is 6. A device can deliver a short bulk-IN frame with skb->len in the 6 to 11 range, or leave a short trailing remainder on a later loop iteration. Either case underflows usb_packet_length to about 65530. That bypasses the usb_packet_length < ether_packet_length truncation path. The device-supplied ether_packet_length, a le16 up to 65535 read from header_start[2], then drives a memcmp() and the following skb_trim() and skb_pull() past the end of the rx buffer. The rx buffer is hard_mtu * 10, which is 14000 bytes. That is an out of bounds read. Require both the start and end framing headers to be present before subtracting them, on every loop iteration. Fixes: d40261236e8e ("net/usb: Add Samsung Kalmia driver for Samsung GT-B3730") Cc: stable@vger.kernel.org Signed-off-by: Maoyi Xie Reviewed-by: Andrew Lunn Link: https://patch.msgid.link/178211531778.2216480.12637613349790980750@maoyixie.com Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/usb/kalmia.c b/drivers/net/usb/kalmia.c index ee9c48f7f68f..0dd0a30c3db4 100644 --- a/drivers/net/usb/kalmia.c +++ b/drivers/net/usb/kalmia.c @@ -276,6 +276,14 @@ kalmia_rx_fixup(struct usbnet *dev, struct sk_buff *skb) "Received header: %6phC. Package length: %i\n", header_start, skb->len - KALMIA_HEADER_LENGTH); + /* both framing headers must be present before we subtract + * them, otherwise usb_packet_length underflows and the + * device-supplied ether_packet_length drives an out of bounds + * access below + */ + if (skb->len < 2 * KALMIA_HEADER_LENGTH) + return 0; + /* subtract start header and end header */ usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH); ether_packet_length = get_unaligned_le16(&header_start[2]);