From 53bc9993ae62cb10f7609f54d9bb78197ee23fec Mon Sep 17 00:00:00 2001 From: Tobi Gaertner Date: Sat, 14 Mar 2026 13:46:39 +0800 Subject: [PATCH] net: usb: cdc_ncm: add ndpoffset to NDP16 nframes bounds check ANBZ: #32863 commit 2aa8a4fa8d5b7d0e1ebcec100e1a4d80a1f4b21a upstream. cdc_ncm_rx_verify_ndp16() validates that the NDP header and its DPE entries fit within the skb. The first check correctly accounts for ndpoffset: if ((ndpoffset + sizeof(struct usb_cdc_ncm_ndp16)) > skb_in->len) but the second check omits it: if ((sizeof(struct usb_cdc_ncm_ndp16) + ret * (sizeof(struct usb_cdc_ncm_dpe16))) > skb_in->len) This validates the DPE array size against the total skb length as if the NDP were at offset 0, rather than at ndpoffset. When the NDP is placed near the end of the NTB (large wNdpIndex), the DPE entries can extend past the skb data buffer even though the check passes. cdc_ncm_rx_fixup() then reads out-of-bounds memory when iterating the DPE array. Add ndpoffset to the nframes bounds check and use struct_size_t() to express the NDP-plus-DPE-array size more clearly. Fixes: ff06ab13a4cc ("net: cdc_ncm: splitting rx_fixup for code reuse") Signed-off-by: Tobi Gaertner Link: https://patch.msgid.link/20260314054640.2895026-2-tob.gaertner@me.com Signed-off-by: Jakub Kicinski Fixes: CVE-2026-23448 Signed-off-by: PatchPilot Signed-off-by: Ferry Meng --- drivers/net/usb/cdc_ncm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index ab91fa5b0194..ed5a3b7145b0 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -1632,6 +1632,7 @@ int cdc_ncm_rx_verify_ndp16(struct sk_buff *skb_in, int ndpoffset) struct usbnet *dev = netdev_priv(skb_in->dev); struct usb_cdc_ncm_ndp16 *ndp16; int ret = -EINVAL; + size_t ndp_len; if ((ndpoffset + sizeof(struct usb_cdc_ncm_ndp16)) > skb_in->len) { netif_dbg(dev, rx_err, dev->net, "invalid NDP offset <%u>\n", @@ -1651,8 +1652,8 @@ int cdc_ncm_rx_verify_ndp16(struct sk_buff *skb_in, int ndpoffset) sizeof(struct usb_cdc_ncm_dpe16)); ret--; /* we process NDP entries except for the last one */ - if ((sizeof(struct usb_cdc_ncm_ndp16) + - ret * (sizeof(struct usb_cdc_ncm_dpe16))) > skb_in->len) { + ndp_len = struct_size_t(struct usb_cdc_ncm_ndp16, dpe16, ret); + if (ndpoffset + ndp_len > skb_in->len) { netif_dbg(dev, rx_err, dev->net, "Invalid nframes = %d\n", ret); ret = -EINVAL; } -- Gitee