From bbad88f111a1829f366c189aa48e7e58e57553fc Mon Sep 17 00:00:00 2001 From: Bob Pearson Date: Fri, 29 Mar 2024 09:55:04 -0500 Subject: RDMA/rxe: Fix seg fault in rxe_comp_queue_pkt [ Upstream commit 2b23b6097303ed0ba5f4bc036a1c07b6027af5c6 ] In rxe_comp_queue_pkt() an incoming response packet skb is enqueued to the resp_pkts queue and then a decision is made whether to run the completer task inline or schedule it. Finally the skb is dereferenced to bump a 'hw' performance counter. This is wrong because if the completer task is already running in a separate thread it may have already processed the skb and freed it which can cause a seg fault. This has been observed infrequently in testing at high scale. This patch fixes this by changing the order of enqueuing the packet until after the counter is accessed. Link: https://lore.kernel.org/r/20240329145513.35381-4-rpearsonhpe@gmail.com Signed-off-by: Bob Pearson Fixes: 0b1e5b99a48b ("IB/rxe: Add port protocol stats") Signed-off-by: Jason Gunthorpe Signed-off-by: Sasha Levin --- drivers/infiniband/sw/rxe/rxe_comp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c index d0bdc2d8adc8..acd2172bf092 100644 --- a/drivers/infiniband/sw/rxe/rxe_comp.c +++ b/drivers/infiniband/sw/rxe/rxe_comp.c @@ -131,12 +131,12 @@ void rxe_comp_queue_pkt(struct rxe_qp *qp, struct sk_buff *skb) { int must_sched; - skb_queue_tail(&qp->resp_pkts, skb); - - must_sched = skb_queue_len(&qp->resp_pkts) > 1; + must_sched = skb_queue_len(&qp->resp_pkts) > 0; if (must_sched != 0) rxe_counter_inc(SKB_TO_PKT(skb)->rxe, RXE_CNT_COMPLETER_SCHED); + skb_queue_tail(&qp->resp_pkts, skb); + if (must_sched) rxe_sched_task(&qp->comp.task); else -- cgit v1.2.3