| Message ID | 20220215103547.29599-1-oneukum@suse.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 8d2b1a1ec9f559d30b724877da4ce592edc41fdc |
| Headers | show |
| Series | CDC-NCM: avoid overflow in sanity checking | expand |
On Tue, Feb 15, 2022 at 11:35:47AM +0100, Oliver Neukum wrote: > A broken device may give an extreme offset like 0xFFF0 > and a reasonable length for a fragment. In the sanity > check as formulated now, this will create an integer > overflow, defeating the sanity check. Both offset > and offset + len need to be checked in such a manner > that no overflow can occur. > And those quantities should be unsigned. > > Signed-off-by: Oliver Neukum <oneukum@suse.com> > --- > drivers/net/usb/cdc_ncm.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c > index e303b522efb5..15f91d691bba 100644 > --- a/drivers/net/usb/cdc_ncm.c > +++ b/drivers/net/usb/cdc_ncm.c > @@ -1715,10 +1715,10 @@ int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in) > { > struct sk_buff *skb; > struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0]; > - int len; > + unsigned int len; > int nframes; > int x; > - int offset; > + unsigned int offset; > union { > struct usb_cdc_ncm_ndp16 *ndp16; > struct usb_cdc_ncm_ndp32 *ndp32; > @@ -1790,8 +1790,8 @@ int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in) > break; > } > > - /* sanity checking */ > - if (((offset + len) > skb_in->len) || > + /* sanity checking - watch out for integer wrap*/ > + if ((offset > skb_in->len) || (len > skb_in->len - offset) || > (len > ctx->rx_max) || (len < ETH_HLEN)) { > netif_dbg(dev, rx_err, dev->net, > "invalid frame detected (ignored) offset[%u]=%u, length=%u, skb=%p\n", > -- > 2.34.1 > Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: stable <stable@vger.kernel.org>
Hello: This patch was applied to netdev/net.git (master) by David S. Miller <davem@davemloft.net>: On Tue, 15 Feb 2022 11:35:47 +0100 you wrote: > A broken device may give an extreme offset like 0xFFF0 > and a reasonable length for a fragment. In the sanity > check as formulated now, this will create an integer > overflow, defeating the sanity check. Both offset > and offset + len need to be checked in such a manner > that no overflow can occur. > And those quantities should be unsigned. > > [...] Here is the summary with links: - CDC-NCM: avoid overflow in sanity checking https://git.kernel.org/netdev/net/c/8d2b1a1ec9f5 You are awesome, thank you!
diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index e303b522efb5..15f91d691bba 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -1715,10 +1715,10 @@ int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in) { struct sk_buff *skb; struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0]; - int len; + unsigned int len; int nframes; int x; - int offset; + unsigned int offset; union { struct usb_cdc_ncm_ndp16 *ndp16; struct usb_cdc_ncm_ndp32 *ndp32; @@ -1790,8 +1790,8 @@ int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in) break; } - /* sanity checking */ - if (((offset + len) > skb_in->len) || + /* sanity checking - watch out for integer wrap*/ + if ((offset > skb_in->len) || (len > skb_in->len - offset) || (len > ctx->rx_max) || (len < ETH_HLEN)) { netif_dbg(dev, rx_err, dev->net, "invalid frame detected (ignored) offset[%u]=%u, length=%u, skb=%p\n",
A broken device may give an extreme offset like 0xFFF0 and a reasonable length for a fragment. In the sanity check as formulated now, this will create an integer overflow, defeating the sanity check. Both offset and offset + len need to be checked in such a manner that no overflow can occur. And those quantities should be unsigned. Signed-off-by: Oliver Neukum <oneukum@suse.com> --- drivers/net/usb/cdc_ncm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)