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authorOliver Neukum <oneukum@suse.com>2022-02-15 13:35:47 +0300
committerDavid S. Miller <davem@davemloft.net>2022-02-15 17:56:10 +0300
commit8d2b1a1ec9f559d30b724877da4ce592edc41fdc (patch)
tree2b5bad2d091e5bf2cb4f403ffb9305250a394594 /drivers
parent7e5b6a5c8c44310784c88c1c198dde79f6402f7b (diff)
downloadlinux-8d2b1a1ec9f559d30b724877da4ce592edc41fdc.tar.xz
CDC-NCM: avoid overflow in sanity checking
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> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/usb/cdc_ncm.c8
1 files 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 @@ next_ndp:
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",