| Message ID | 20250105010121.12546-5-forst@pen.gy (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | usbnet: ipheth: prevent OoB reads of NDP16 | expand |
On Sun, Jan 05, 2025 at 02:01:18AM +0100, Foster Snowhill wrote: > Original code allowed for the start of NDP16 to be anywhere within the > URB based on the `wNdpIndex` value in NTH16. Only the start position of > NDP16 was checked, so it was possible for even the fixed-length part > of NDP16 to extend past the end of URB, leading to an out-of-bounds > read. > > On iOS devices, the NDP16 header always directly follows NTH16. Rely on > and check for this specific format. > > This, along with NCM-specific minimal URB length check that already > exists, will ensure that the fixed-length part of NDP16 plus a set > amount of DPEs fit within the URB. > > Note that this commit alone does not fully address the OoB read. > The limit on the amount of DPEs needs to be enforced separately. > > Fixes: a2d274c62e44 ("usbnet: ipheth: add CDC NCM support") > Signed-off-by: Foster Snowhill <forst@pen.gy> > --- > v4: > Additionally check that ncmh->wNdpIndex points immediately after > NTH16. This covers an unexpected on real devices, and highly > unlikely otherwise, case where the bytes after NTH16 are set to > `USB_CDC_NCM_NDP16_NOCRC_SIGN`, yet aren't the beginning of the > NDP16 header. > v3: https://lore.kernel.org/netdev/20241123235432.821220-4-forst@pen.gy/ > Split out from a monolithic patch in v2 as an atomic change. > v2: https://lore.kernel.org/netdev/20240912211817.1707844-1-forst@pen.gy/ > No code changes. Update commit message to further clarify that > `ipheth` is not and does not aim to be a complete or spec-compliant > CDC NCM implementation. > v1: https://lore.kernel.org/netdev/20240907230108.978355-1-forst@pen.gy/ > --- > drivers/net/usb/ipheth.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c > index 48c79e69bb7b..35f507db2c4a 100644 > --- a/drivers/net/usb/ipheth.c > +++ b/drivers/net/usb/ipheth.c > @@ -237,15 +237,14 @@ static int ipheth_rcvbulk_callback_ncm(struct urb *urb) > > ncmh = urb->transfer_buffer; > if (ncmh->dwSignature != cpu_to_le32(USB_CDC_NCM_NTH16_SIGN) || > - le16_to_cpu(ncmh->wNdpIndex) >= urb->actual_length) { > + /* On iOS, NDP16 directly follows NTH16 */ > + ncmh->wNdpIndex != cpu_to_le16(sizeof(struct usb_cdc_ncm_nth16))) { > dev->net->stats.rx_errors++; > return retval; > } > > - ncm0 = urb->transfer_buffer + le16_to_cpu(ncmh->wNdpIndex); > - if (ncm0->dwSignature != cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN) || > - le16_to_cpu(ncmh->wHeaderLength) + le16_to_cpu(ncm0->wLength) >= > - urb->actual_length) { > + ncm0 = urb->transfer_buffer + sizeof(struct usb_cdc_ncm_nth16); > + if (ncm0->dwSignature != cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN)) { > dev->net->stats.rx_errors++; > return retval; > } > -- > 2.45.1 > > Hi, This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him a patch that has triggered this response. He used to manually respond to these common problems, but in order to save his sanity (he kept writing the same thing over and over, yet to different people), I was created. Hopefully you will not take offence and will fix the problem in your patch and resubmit it so that it can be accepted into the Linux kernel tree. You are receiving this message because of the following common error(s) as indicated below: - You have marked a patch with a "Fixes:" tag for a commit that is in an older released kernel, yet you do not have a cc: stable line in the signed-off-by area at all, which means that the patch will not be applied to any older kernel releases. To properly fix this, please follow the documented rules in the Documentation/process/stable-kernel-rules.rst file for how to resolve this. If you wish to discuss this problem further, or you have questions about how to resolve this issue, please feel free to respond to this email and Greg will reply once he has dug out from the pending patches received from other developers. thanks, greg k-h's patch email bot
diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c index 48c79e69bb7b..35f507db2c4a 100644 --- a/drivers/net/usb/ipheth.c +++ b/drivers/net/usb/ipheth.c @@ -237,15 +237,14 @@ static int ipheth_rcvbulk_callback_ncm(struct urb *urb) ncmh = urb->transfer_buffer; if (ncmh->dwSignature != cpu_to_le32(USB_CDC_NCM_NTH16_SIGN) || - le16_to_cpu(ncmh->wNdpIndex) >= urb->actual_length) { + /* On iOS, NDP16 directly follows NTH16 */ + ncmh->wNdpIndex != cpu_to_le16(sizeof(struct usb_cdc_ncm_nth16))) { dev->net->stats.rx_errors++; return retval; } - ncm0 = urb->transfer_buffer + le16_to_cpu(ncmh->wNdpIndex); - if (ncm0->dwSignature != cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN) || - le16_to_cpu(ncmh->wHeaderLength) + le16_to_cpu(ncm0->wLength) >= - urb->actual_length) { + ncm0 = urb->transfer_buffer + sizeof(struct usb_cdc_ncm_nth16); + if (ncm0->dwSignature != cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN)) { dev->net->stats.rx_errors++; return retval; }
Original code allowed for the start of NDP16 to be anywhere within the URB based on the `wNdpIndex` value in NTH16. Only the start position of NDP16 was checked, so it was possible for even the fixed-length part of NDP16 to extend past the end of URB, leading to an out-of-bounds read. On iOS devices, the NDP16 header always directly follows NTH16. Rely on and check for this specific format. This, along with NCM-specific minimal URB length check that already exists, will ensure that the fixed-length part of NDP16 plus a set amount of DPEs fit within the URB. Note that this commit alone does not fully address the OoB read. The limit on the amount of DPEs needs to be enforced separately. Fixes: a2d274c62e44 ("usbnet: ipheth: add CDC NCM support") Signed-off-by: Foster Snowhill <forst@pen.gy> --- v4: Additionally check that ncmh->wNdpIndex points immediately after NTH16. This covers an unexpected on real devices, and highly unlikely otherwise, case where the bytes after NTH16 are set to `USB_CDC_NCM_NDP16_NOCRC_SIGN`, yet aren't the beginning of the NDP16 header. v3: https://lore.kernel.org/netdev/20241123235432.821220-4-forst@pen.gy/ Split out from a monolithic patch in v2 as an atomic change. v2: https://lore.kernel.org/netdev/20240912211817.1707844-1-forst@pen.gy/ No code changes. Update commit message to further clarify that `ipheth` is not and does not aim to be a complete or spec-compliant CDC NCM implementation. v1: https://lore.kernel.org/netdev/20240907230108.978355-1-forst@pen.gy/ --- drivers/net/usb/ipheth.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)