diff options
| author | Jason Xing <kernelxing@tencent.com> | 2026-05-02 23:07:19 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-05-06 05:27:50 +0300 |
| commit | 3dec153ae484e3b2ddac841156e197ba54c8df94 (patch) | |
| tree | 39f1736e97855cd758ea24f6fffd70b02505dbff | |
| parent | 0f3776583d282550dbafe6082a914efcf9094d59 (diff) | |
| download | linux-3dec153ae484e3b2ddac841156e197ba54c8df94.tar.xz | |
xsk: prevent CQ desync when freeing half-built skbs in xsk_build_skb()
Once xsk_skb_init_misc() has been called on an skb, its destructor is
set to xsk_destruct_skb(), which submits the descriptor address(es) to
the completion queue and advances the CQ producer. If such an skb is
subsequently freed via kfree_skb() along an error path - before the
skb has ever been handed to the driver - the destructor still runs and
submits a bogus, half-initialized address to the CQ.
Postpone the init phase when we believe the allocation of first frag is
successfully completed. Before this init, skb can be safely freed by
kfree_skb().
Closes: https://lore.kernel.org/all/20260419045822.843BFC2BCAF@smtp.kernel.org/
Fixes: c30d084960cf ("xsk: avoid overwriting skb fields for multi-buffer traffic")
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://patch.msgid.link/20260502200722.53960-6-kerneljasonxing@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/xdp/xsk.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 55378c3855d5..af3c5752bb63 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -819,8 +819,6 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, return ERR_PTR(err); skb_reserve(skb, hr); - - xsk_skb_init_misc(skb, xs, desc->addr); if (desc->options & XDP_TX_METADATA) { err = xsk_skb_metadata(skb, buffer, desc, pool, hr); if (unlikely(err)) @@ -917,7 +915,6 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, if (unlikely(err)) goto free_err; - xsk_skb_init_misc(skb, xs, desc->addr); if (desc->options & XDP_TX_METADATA) { err = xsk_skb_metadata(skb, buffer, desc, xs->pool, hr); @@ -967,6 +964,8 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, } } + if (!xs->skb) + xsk_skb_init_misc(skb, xs, desc->addr); xsk_inc_num_desc(skb); return skb; |