[PATCH 6.12 330/567] RDMA/irdma: avoid invalid read in irdma_net_event

Greg Kroah-Hartman
2026-01-06T17:32:27Z

From: Michal Schmidt <mschmidt@redhat.com>

[ Upstream commit 6f05611728e9d0ab024832a4f1abb74a5f5d0bb0 ]

irdma_net_event() should not dereference anything from "neigh" (alias
"ptr") until it has checked that the event is NETEVENT_NEIGH_UPDATE.
Other events come with different structures pointed to by "ptr" and they
may be smaller than struct neighbour.

Move the read of neigh->dev under the NETEVENT_NEIGH_UPDATE case.

The bug is mostly harmless, but it triggers KASAN on debug kernels:

BUG: KASAN: stack-out-of-bounds in irdma_net_event+0x32e/0x3b0 [irdma]
Read of size 8 at addr ffffc900075e07f0 by task kworker/27:2/542554

CPU: 27 PID: 542554 Comm: kworker/27:2 Kdump: loaded Not tainted 5.14.0-630.el9.x86_64+debug #1
Hardware name: [...]
Workqueue: events rt6_probe_deferred
Call Trace:
<IRQ>
dump_stack_lvl+0x60/0xb0
print_address_description.constprop.0+0x2c/0x3f0
print_report+0xb4/0x270
kasan_report+0x92/0xc0
irdma_net_event+0x32e/0x3b0 [irdma]
notifier_call_chain+0x9e/0x180
atomic_notifier_call_chain+0x5c/0x110
rt6_do_redirect+0xb91/0x1080
tcp_v6_err+0xe9b/0x13e0
icmpv6_notify+0x2b2/0x630
ndisc_redirect_rcv+0x328/0x530
icmpv6_rcv+0xc16/0x1360
ip6_protocol_deliver_rcu+0xb84/0x12e0
ip6_input_finish+0x117/0x240
ip6_input+0xc4/0x370
ipv6_rcv+0x420/0x7d0
__netif_receive_skb_one_core+0x118/0x1b0
process_backlog+0xd1/0x5d0
__napi_poll.constprop.0+0xa3/0x440
net_rx_action+0x78a/0xba0
handle_softirqs+0x2d4/0x9c0
do_softirq+0xad/0xe0
</IRQ>

Fixes: 915cc7ac0f8e ("RDMA/irdma: Add miscellaneous utility definitions")
Link: https://patch.msgid.link/r/20251127143150.121099-1-mschmidt@redhat.com
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/infiniband/hw/irdma/utils.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/irdma/utils.c b/drivers/infiniband/hw/irdma/utils.c
index 0422787592d8..87a6d58663de 100644
--- a/drivers/infiniband/hw/irdma/utils.c
+++ b/drivers/infiniband/hw/irdma/utils.c
@@ -251,7 +251,7 @@ int irdma_net_event(struct notifier_block *notifier, unsigned long event,
void *ptr)
{
struct neighbour *neigh = ptr;
- struct net_device *real_dev, *netdev = (struct net_device *)neigh->dev;
+ struct net_device *real_dev, *netdev;
struct irdma_device *iwdev;
struct ib_device *ibdev;
__be32 *p;
@@ -260,6 +260,7 @@ int irdma_net_event(struct notifier_block *notifier, unsigned long event,

switch (event) {
case NETEVENT_NEIGH_UPDATE:
+ netdev = neigh->dev;
real_dev = rdma_vlan_dev_real_dev(netdev);
if (!real_dev)
real_dev = netdev;
--
2.51.0