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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") > Signed-off-by: Jason Xing > --- > net/xdp/xsk.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c > index d23d1b14b8b4..88ec6d2cbbcf 100644 > --- a/net/xdp/xsk.c > +++ b/net/xdp/xsk.c > @@ -739,8 +739,6 @@ 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)) > @@ -834,7 +832,6 @@ 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); > @@ -884,6 +881,8 @@ 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; > -- > 2.41.3 > Acked-by: Stanislav Fomichev