This is a note to let you know that I've just added the patch titled
RDMA/rxe: Fix seg fault in rxe_comp_queue_pkt
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rdma-rxe-fix-seg-fault-in-rxe_comp_queue_pkt.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 985cd66e2c3441be2e1e1c95e38b5a0f36429999
Author: Bob Pearson <rpearsonhpe@xxxxxxxxx>
Date: Fri Mar 29 09:55:04 2024 -0500
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@xxxxxxxxx
Signed-off-by: Bob Pearson <rpearsonhpe@xxxxxxxxx>
Fixes: 0b1e5b99a48b ("IB/rxe: Add port protocol stats")
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c
index d0bdc2d8adc82..acd2172bf092b 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
