5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Antoine Tenart atenart@kernel.org
[ Upstream commit ee01b2f2d7d0010787c2343463965bbc283a497f ]
In __udp_gso_segment the skb destructor is removed before segmenting the skb but the socket reference is kept as-is. This is an issue if the original skb is later orphaned as we can hit the following bug:
kernel BUG at ./include/linux/skbuff.h:3312! (skb_orphan) RIP: 0010:ip_rcv_core+0x8b2/0xca0 Call Trace: ip_rcv+0xab/0x6e0 __netif_receive_skb_one_core+0x168/0x1b0 process_backlog+0x384/0x1100 __napi_poll.constprop.0+0xa1/0x370 net_rx_action+0x925/0xe50
The above can happen following a sequence of events when using OpenVSwitch, when an OVS_ACTION_ATTR_USERSPACE action precedes an OVS_ACTION_ATTR_OUTPUT action:
1. OVS_ACTION_ATTR_USERSPACE is handled (in do_execute_actions): the skb goes through queue_gso_packets and then __udp_gso_segment, where its destructor is removed. 2. The segments' data are copied and sent to userspace. 3. OVS_ACTION_ATTR_OUTPUT is handled (in do_execute_actions) and the same original skb is sent to its path. 4. If it later hits skb_orphan, we hit the bug.
Fix this by also removing the reference to the socket in __udp_gso_segment.
Fixes: ad405857b174 ("udp: better wmem accounting on gso") Signed-off-by: Antoine Tenart atenart@kernel.org Link: https://patch.msgid.link/20250226171352.258045-1-atenart@kernel.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/udp_offload.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 487a92d75c703..6505a6fd245a6 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -204,13 +204,17 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
/* clear destructor to avoid skb_segment assigning it to tail */ copy_dtor = gso_skb->destructor == sock_wfree; - if (copy_dtor) + if (copy_dtor) { gso_skb->destructor = NULL; + gso_skb->sk = NULL; + }
segs = skb_segment(gso_skb, features); if (IS_ERR_OR_NULL(segs)) { - if (copy_dtor) + if (copy_dtor) { gso_skb->destructor = sock_wfree; + gso_skb->sk = sk; + } return segs; }