From: Bob Pearson Date: Fri, 29 Mar 2024 14:55:04 +0000 (-0500) Subject: RDMA/rxe: Fix seg fault in rxe_comp_queue_pkt X-Git-Tag: v6.10-rc1~109^2~36 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2b23b6097303ed0ba5f4bc036a1c07b6027af5c6;p=thirdparty%2Fkernel%2Fstable.git RDMA/rxe: Fix seg fault in rxe_comp_queue_pkt 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 --- diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c index b78b8c0856abd..c997b7cbf2a9e 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