* [PATCH] CDC-NCM: avoid overflow in sanity checking
@ 2022-02-15 10:35 Oliver Neukum
2022-02-15 13:30 ` Greg KH
2022-02-15 15:00 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Oliver Neukum @ 2022-02-15 10:35 UTC (permalink / raw)
To: davem, kuba, gregKH, netdev, linux-usb; +Cc: Oliver Neukum
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] CDC-NCM: avoid overflow in sanity checking
2022-02-15 10:35 [PATCH] CDC-NCM: avoid overflow in sanity checking Oliver Neukum
@ 2022-02-15 13:30 ` Greg KH
2022-02-15 15:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Greg KH @ 2022-02-15 13:30 UTC (permalink / raw)
To: Oliver Neukum; +Cc: davem, kuba, netdev, linux-usb
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>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] CDC-NCM: avoid overflow in sanity checking
2022-02-15 10:35 [PATCH] CDC-NCM: avoid overflow in sanity checking Oliver Neukum
2022-02-15 13:30 ` Greg KH
@ 2022-02-15 15:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-02-15 15:00 UTC (permalink / raw)
To: Oliver Neukum; +Cc: davem, kuba, gregKH, netdev, linux-usb
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!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-02-15 15:00 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-02-15 10:35 [PATCH] CDC-NCM: avoid overflow in sanity checking Oliver Neukum
2022-02-15 13:30 ` Greg KH
2022-02-15 15:00 ` patchwork-bot+netdevbpf
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.