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1f6f88105e
Previously, __skb_frag_ref() and skb_frag_ref() unconditionally
incremented the non-pp backing refcount via get_netmem(), while
skb_frag_unref() decremented pp_ref_count whenever skb->pp_recycle was
set. Ref-ing a page_pool fragment into a pp_recycle=1 SKB (or clearing
pp_recycle=0 on an uncloned SKB while clones still held pp_recycle=1)
leaked the backing non-pp refcount and underflowed pp_ref_count across
IP-TFS, skb_split(), skb_shift(), and cloned unclone paths.
Replace __skb_frag_ref() with skb_netmem_ref(netmem, recycle) as the
exact counterpart to skb_netmem_unref(netmem, recycle):
- Keep skb->pp_recycle intact in skb_release_data() so uncloning paths
(pskb_expand_head() and pskb_carve_inside_{header,nonlinear}()) keep
trading pp_ref_count references symmetrically across clones.
- Propagate pp_recycle and call skb_frag_ref() on the destination SKB in
__pskb_copy_fclone(), skb_zerocopy(), skb_split(), skb_shift(), and
skb_segment().
- Linearize an output segment's existing frags in skb_segment() before
attaching frags from a frag_list SKB with a different pp_recycle bit,
since each output segment carries a single pp_recycle bit.
- Use skb_frag_ref() in xfrm_iptfs, chcr_ktls, and cassini, and call
get_netmem() directly in veth and tls_device_fallback where callers
explicitly take a raw non-pp reference.
Found by code inspection while reviewing the IP-TFS pp_ref_count fix [1]
and confirmed with the KUnit tests added later in this series; not
observed in production. The xfrm_iptfs, chcr_ktls, cassini, veth, and
tls_device_fallback changes are compile-tested only.
Link: https://lore.kernel.org/netdev/xfrm-iptfs-pp_ref_count-underflow-v4-1-912fa72106f0@secunet.com/ [1]
Cc: Antony Antony <antony.antony@secunet.com>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jesper Dangaard Brouer <hawk@kernel.org>
Cc: bpf@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Mina Almasry <almasrymina@google.com>
Tested-by: Antony Antony <antony.antony@secunet.com>
Link: https://patch.msgid.link/20261014173945.373295-5-almasrymina@google.com
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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|---|---|---|
| .. | ||
| espintcp.c | ||
| Kconfig | ||
| Makefile | ||
| trace_iptfs.h | ||
| xfrm_algo.c | ||
| xfrm_compat.c | ||
| xfrm_device.c | ||
| xfrm_hash.c | ||
| xfrm_hash.h | ||
| xfrm_inout.h | ||
| xfrm_input.c | ||
| xfrm_interface_bpf.c | ||
| xfrm_interface_core.c | ||
| xfrm_ipcomp.c | ||
| xfrm_iptfs.c | ||
| xfrm_nat_keepalive.c | ||
| xfrm_output.c | ||
| xfrm_policy.c | ||
| xfrm_proc.c | ||
| xfrm_replay.c | ||
| xfrm_state_bpf.c | ||
| xfrm_state.c | ||
| xfrm_sysctl.c | ||
| xfrm_user.c | ||