5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bob Pearson <rpearsonhpe@xxxxxxxxx> 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@xxxxxxxxx Signed-off-by: Bob Pearson <rpearsonhpe@xxxxxxxxx> Fixes: 0b1e5b99a48b ("IB/rxe: Add port protocol stats") Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx> [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 <sherry.yang@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/infiniband/sw/rxe/rxe_comp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/infiniband/sw/rxe/rxe_comp.c +++ b/drivers/infiniband/sw/rxe/rxe_comp.c @@ -150,12 +150,12 @@ void rxe_comp_queue_pkt(struct rxe_qp *q { 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); }
