From de5a059e36657442b5637cc16df5163e435b9cb4 Mon Sep 17 00:00:00 2001 From: Bob Pearson Date: Fri, 29 Mar 2024 09:55:04 -0500 Subject: [PATCH] RDMA/rxe: Fix seg fault in rxe_comp_queue_pkt commit 2b23b6097303ed0ba5f4bc036a1c07b6027af5c6 upstream. 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 [Sherry: bp to fix CVE-2024-38544. Fix conflict due to missing commit: dccb23f6c312 ("RDMA/rxe: Split rxe_run_task() into two subroutines") which is not necessary to backport] Signed-off-by: Sherry Yang Signed-off-by: Greg Kroah-Hartman --- 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 0a1e6393250b..a54d80004342 100644 --- a/drivers/infiniband/sw/rxe/rxe_comp.c +++ b/drivers/infiniband/sw/rxe/rxe_comp.c @@ -123,12 +123,12 @@ 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); + rxe_run_task(&qp->comp.task, must_sched); }