From: Weiming Shi Date: Thu, 21 May 2026 16:32:31 +0000 (-0700) Subject: tap: free page on error paths in tap_get_user_xdp() X-Git-Tag: v7.1-rc6~27^2~35 X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=3bcf7aec6a9d16438f2cec29f5d7c8d5b8edf9b2;p=thirdparty%2Fkernel%2Flinux.git tap: free page on error paths in tap_get_user_xdp() tap_get_user_xdp() rejects a frame shorter than ETH_HLEN with -EINVAL, and returns -ENOMEM when build_skb() fails. Both paths jump to the err label without freeing the page that vhost_net_build_xdp() allocated for the frame. tap_sendmsg() discards the per-buffer return value and always returns 0, so vhost_tx_batch() takes the success path and never frees the page; each rejected frame in a batch leaks one page-frag chunk. Free the page on both error paths, before the skb is built. This is the tap counterpart of the same leak in tun_xdp_one(). Fixes: 0efac27791ee ("tap: accept an array of XDP buffs through sendmsg()") Fixes: ed7f2afdd0e0 ("tap: add missing verification for short frame") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Reviewed-by: Dongli Zhang Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260521163230.1478627-2-bestswngs@gmail.com Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/tap.c b/drivers/net/tap.c index a590e07ce0a9..fae115915c8e 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -1052,6 +1052,7 @@ static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp) int err, depth; if (unlikely(xdp->data_end - xdp->data < ETH_HLEN)) { + put_page(virt_to_head_page(xdp->data)); err = -EINVAL; goto err; } @@ -1061,6 +1062,7 @@ static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp) skb = build_skb(xdp->data_hard_start, buflen); if (!skb) { + put_page(virt_to_head_page(xdp->data)); err = -ENOMEM; goto err; }