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authorBjørn Mork <bjorn@mork.no>2014-05-02 23:27:00 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-05-31 13:20:36 -0700
commit19ca28c306fcf825c165f6f3b9532bec479a60b4 (patch)
tree6852255ce8b640c72d9224edfc5e8fd0ebb0b19b
parent1b3ac8488ee4a5dd42b6c1809ca8e80fb64c549c (diff)
net: cdc_ncm: fix buffer overflow
[ Upstream commit 9becd707841207652449a8dfd90fe9c476d88546 ] Commit 4d619f625a60 ("net: cdc_ncm: no point in filling up the NTBs if we send ZLPs") changed the padding logic for devices with the ZLP flag set. This meant that frames of any size will be sent without additional padding, except for the single byte added if the size is a multiple of the USB packet size. But if the unpadded size is identical to the maximum frame size, and the maximum size is a multiplum of the USB packet size, then this one-byte padding will overflow the buffer. Prevent padding if already at maximum frame size, letting usbnet transmit a ZLP instead in this case. Fixes: 4d619f625a60 ("net: cdc_ncm: no point in filling up the NTBs if we send ZLPs") Reported by: Yu-an Shih <yshih@nvidia.com> Signed-off-by: Bjørn Mork <bjorn@mork.no> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/net/usb/cdc_ncm.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index d350d2795e10..75d7d9dbbe35 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -768,7 +768,7 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign)
skb_out->len > CDC_NCM_MIN_TX_PKT)
memset(skb_put(skb_out, ctx->tx_max - skb_out->len), 0,
ctx->tx_max - skb_out->len);
- else if ((skb_out->len % dev->maxpacket) == 0)
+ else if (skb_out->len < ctx->tx_max && (skb_out->len % dev->maxpacket) == 0)
*skb_put(skb_out, 1) = 0; /* force short packet */
/* set final frame length */