From 833d0b78136a27fbf01ef55c78ecde6325a3b2d0 Mon Sep 17 00:00:00 2001 From: Felix Maurer Date: Tue, 11 Mar 2025 08:51:19 +0900 Subject: [PATCH] xsk: Free skb when TX metadata options are invalid MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit BugLink: https://bugs.launchpad.net/bugs/2101915 [ Upstream commit 0c0d0f42ffa6ac94cd79893b7ed419c15e1b45de ] When a new skb is allocated for transmitting an xsk descriptor, i.e., for every non-multibuf descriptor or the first frag of a multibuf descriptor, but the descriptor is later found to have invalid options set for the TX metadata, the new skb is never freed. This can leak skbs until the send buffer is full which makes sending more packets impossible. Fix this by freeing the skb in the error path if we are currently dealing with the first frag, i.e., an skb allocated in this iteration of xsk_build_skb. Fixes: 48eb03dd2630 ("xsk: Add TX timestamp and TX checksum offload support") Reported-by: Michal Schmidt Signed-off-by: Felix Maurer Reviewed-by: Toke Høiland-Jørgensen Acked-by: Stanislav Fomichev Acked-by: Martin KaFai Lau Link: https://patch.msgid.link/edb9b00fb19e680dff5a3350cd7581c5927975a8.1731581697.git.fmaurer@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin CVE-2024-53236 Signed-off-by: Koichiro Den Signed-off-by: Stefan Bader --- net/xdp/xsk.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 7d1c0986f9bb..658475a67b4c 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -686,6 +686,8 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, len = desc->len; if (!skb) { + first_frag = true; + hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(dev->needed_headroom)); tr = dev->needed_tailroom; skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err); @@ -696,12 +698,8 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, skb_put(skb, len); err = skb_store_bits(skb, 0, buffer, len); - if (unlikely(err)) { - kfree_skb(skb); + if (unlikely(err)) goto free_err; - } - - first_frag = true; } else { int nr_frags = skb_shinfo(skb)->nr_frags; struct page *page; @@ -769,6 +767,9 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, return skb; free_err: + if (first_frag && skb) + kfree_skb(skb); + if (err == -EOVERFLOW) { /* Drop the packet */ xsk_set_destructor_arg(xs->skb);