From: Si-Wei Liu si-wei.liu@oracle.com

stable inclusion from stable-v6.6.43 commit aa6a5704cab861c9b2ae9f475076e1881e87f5aa category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAG8ZG CVE: CVE-2024-41090

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit ed7f2afdd0e043a397677e597ced0830b83ba0b3 upstream.

The cited commit missed to check against the validity of the frame length in the tap_get_user_xdp() path, which could cause a corrupted skb to be sent downstack. Even before the skb is transmitted, the tap_get_user_xdp()-->skb_set_network_header() may assume the size is more than ETH_HLEN. Once transmitted, this could either cause out-of-bound access beyond the actual length, or confuse the underlayer with incorrect or inconsistent header length in the skb metadata.

In the alternative path, tap_get_user() already prohibits short frame which has the length less than Ethernet header size from being transmitted.

This is to drop any frame shorter than the Ethernet header size just like how tap_get_user() does.

CVE: CVE-2024-41090 Link: https://lore.kernel.org/netdev/1717026141-25716-1-git-send-email-si-wei.liu@... Fixes: 0efac27791ee ("tap: accept an array of XDP buffs through sendmsg()") Cc: stable@vger.kernel.org Signed-off-by: Si-Wei Liu si-wei.liu@oracle.com Signed-off-by: Dongli Zhang dongli.zhang@oracle.com Reviewed-by: Willem de Bruijn willemb@google.com Reviewed-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Jason Wang jasowang@redhat.com Link: https://patch.msgid.link/20240724170452.16837-2-dongli.zhang@oracle.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Liu Jian liujian56@huawei.com --- drivers/net/tap.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c index 5c01cc7b9949..e7212a64a591 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -1177,6 +1177,11 @@ static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp) struct sk_buff *skb; int err, depth;

+ if (unlikely(xdp->data_end - xdp->data < ETH_HLEN)) { + err = -EINVAL; + goto err; + } + if (q->flags & IFF_VNET_HDR) vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);