| Message ID | 20230313220124.52437-1-szymon.heidrich@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | net: usb: smsc95xx: Limit packet length to skb->len | expand |
On Mon, 13 Mar 2023 23:01:24 +0100 Szymon Heidrich wrote: > Packet length retrieved from skb data may be larger than nit: s/skb data/descriptor/ may be better in terms of terminology > the actual socket buffer length (up to 1526 bytes). In such nit: the "up to 1526 bytes" is a bit confusing, I'd remove it. > case the cloned skb passed up the network stack will leak > kernel memory contents. > Fixes: 2f7ca802bdae ("net: Add SMSC LAN9500 USB2.0 10/100 ethernet adapter driver") > Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com> > --- > drivers/net/usb/smsc95xx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c > index 32d2c60d3..ba766bdb2 100644 > --- a/drivers/net/usb/smsc95xx.c > +++ b/drivers/net/usb/smsc95xx.c > @@ -1851,7 +1851,8 @@ static int smsc95xx_rx_fixup(struct usbnet *dev, struct sk_buff *skb) > } > } else { > /* ETH_FRAME_LEN + 4(CRC) + 2(COE) + 4(Vlan) */ > - if (unlikely(size > (ETH_FRAME_LEN + 12))) { > + if (unlikely(size > (ETH_FRAME_LEN + 12) || > + size > skb->len)) { We need this check on both sides of the big if {} statement. In case the error bit is set and we drop the packet we still end up in skb_pull() which if size > skb->len will panic the kernel. So let's do this check right after size and align are calculated? The patch for smsc75xx has sadly already been applied so you'll need to prepare a fix to the fix :( > netif_dbg(dev, rx_err, dev->net, > "size err header=0x%08x\n", header); > return 0;
On 16/03/2023 05:24, Jakub Kicinski wrote: > On Mon, 13 Mar 2023 23:01:24 +0100 Szymon Heidrich wrote: >> Packet length retrieved from skb data may be larger than > > nit: s/skb data/descriptor/ may be better in terms of terminology > >> the actual socket buffer length (up to 1526 bytes). In such > > nit: the "up to 1526 bytes" is a bit confusing, I'd remove it. > >> case the cloned skb passed up the network stack will leak >> kernel memory contents. > > > >> Fixes: 2f7ca802bdae ("net: Add SMSC LAN9500 USB2.0 10/100 ethernet adapter driver") >> Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com> >> --- >> drivers/net/usb/smsc95xx.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c >> index 32d2c60d3..ba766bdb2 100644 >> --- a/drivers/net/usb/smsc95xx.c >> +++ b/drivers/net/usb/smsc95xx.c >> @@ -1851,7 +1851,8 @@ static int smsc95xx_rx_fixup(struct usbnet *dev, struct sk_buff *skb) >> } >> } else { >> /* ETH_FRAME_LEN + 4(CRC) + 2(COE) + 4(Vlan) */ >> - if (unlikely(size > (ETH_FRAME_LEN + 12))) { >> + if (unlikely(size > (ETH_FRAME_LEN + 12) || >> + size > skb->len)) { > > We need this check on both sides of the big if {} statement. > > In case the error bit is set and we drop the packet we still > end up in skb_pull() which if size > skb->len will panic the > kernel. > > So let's do this check right after size and align are calculated? > The patch for smsc75xx has sadly already been applied so you'll > need to prepare a fix to the fix :( > >> netif_dbg(dev, rx_err, dev->net, >> "size err header=0x%08x\n", header); >> return 0; > Thank you very much for you suggestions Kuba, I provided an updated patch for smsc95xx and a new patch addressing smsc75xx. Please let me know in case additional amendments are required.
diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c index 32d2c60d3..ba766bdb2 100644 --- a/drivers/net/usb/smsc95xx.c +++ b/drivers/net/usb/smsc95xx.c @@ -1851,7 +1851,8 @@ static int smsc95xx_rx_fixup(struct usbnet *dev, struct sk_buff *skb) } } else { /* ETH_FRAME_LEN + 4(CRC) + 2(COE) + 4(Vlan) */ - if (unlikely(size > (ETH_FRAME_LEN + 12))) { + if (unlikely(size > (ETH_FRAME_LEN + 12) || + size > skb->len)) { netif_dbg(dev, rx_err, dev->net, "size err header=0x%08x\n", header); return 0;
Packet length retrieved from skb data may be larger than the actual socket buffer length (up to 1526 bytes). In such case the cloned skb passed up the network stack will leak kernel memory contents. Fixes: 2f7ca802bdae ("net: Add SMSC LAN9500 USB2.0 10/100 ethernet adapter driver") Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com> --- drivers/net/usb/smsc95xx.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)