[PATCH 6.19 248/342] net: macb: Protect access to net_device::ip_ptr with RCU lock

Greg Kroah-Hartman
2026-03-31T16:41:56Z

From: Kevin Hao <haokexin@gmail.com>

commit baa35a698cea26930679a20a7550bbb4c8319725 upstream.

Access to net_device::ip_ptr and its associated members must be
protected by an RCU lock. Since we are modifying this piece of code,
let's also move it to execute only when WAKE_ARP is enabled.

To minimize the duration of the RCU lock, a local variable is used to
temporarily store the IP address. This change resolves the following
RCU check warning:
WARNING: suspicious RCU usage
7.0.0-rc3-next-20260310-yocto-standard+ #122 Not tainted
-----------------------------
drivers/net/ethernet/cadence/macb_main.c:5944 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1
5 locks held by rtcwake/518:
#0: ffff000803ab1408 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0xf8/0x368
#1: ffff0008090bf088 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_fop_write_iter+0xbc/0x1c8
#2: ffff00080098d588 (kn->active#70){.+.+}-{0:0}, at: kernfs_fop_write_iter+0xcc/0x1c8
#3: ffff800081c84888 (system_transition_mutex){+.+.}-{4:4}, at: pm_suspend+0x1ec/0x290
#4: ffff0008009ba0f8 (&dev->mutex){....}-{4:4}, at: device_suspend+0x118/0x4f0

stack backtrace:
CPU: 3 UID: 0 PID: 518 Comm: rtcwake Not tainted 7.0.0-rc3-next-20260310-yocto-standard+ #122 PREEMPT
Hardware name: ZynqMP ZCU102 Rev1.1 (DT)
Call trace:
show_stack+0x24/0x38 (C)
__dump_stack+0x28/0x38
dump_stack_lvl+0x64/0x88
dump_stack+0x18/0x24
lockdep_rcu_suspicious+0x134/0x1d8
macb_suspend+0xd8/0x4c0
device_suspend+0x218/0x4f0
dpm_suspend+0x244/0x3a0
dpm_suspend_start+0x50/0x78
suspend_devices_and_enter+0xec/0x560
pm_suspend+0x194/0x290
state_store+0x110/0x158
kobj_attr_store+0x1c/0x30
sysfs_kf_write+0xa8/0xd0
kernfs_fop_write_iter+0x11c/0x1c8
vfs_write+0x248/0x368
ksys_write+0x7c/0xf8
__arm64_sys_write+0x28/0x40
invoke_syscall+0x4c/0xe8
el0_svc_common+0x98/0xf0
do_el0_svc+0x28/0x40
el0_svc+0x54/0x1e0
el0t_64_sync_handler+0x84/0x130
el0t_64_sync+0x198/0x1a0

Fixes: 0cb8de39a776 ("net: macb: Add ARP support to WOL")
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Cc: stable@vger.kernel.org
Reviewed-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://patch.msgid.link/20260318-macb-irq-v2-2-f1179768ab24@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/cadence/macb_main.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)

--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -5773,9 +5773,9 @@ static int __maybe_unused macb_suspend(s
struct macb_queue *queue;
struct in_device *idev;
unsigned long flags;
+ u32 tmp, ifa_local;
unsigned int q;
int err;
- u32 tmp;

if (!device_may_wakeup(&bp->dev->dev))
phy_exit(bp->phy);
@@ -5784,14 +5784,21 @@ static int __maybe_unused macb_suspend(s
return 0;

if (bp->wol & MACB_WOL_ENABLED) {
- /* Check for IP address in WOL ARP mode */
- idev = __in_dev_get_rcu(bp->dev);
- if (idev)
- ifa = rcu_dereference(idev->ifa_list);
- if ((bp->wolopts & WAKE_ARP) && !ifa) {
- netdev_err(netdev, "IP address not assigned as required by WoL walk ARP\n");
- return -EOPNOTSUPP;
+ if (bp->wolopts & WAKE_ARP) {
+ /* Check for IP address in WOL ARP mode */
+ rcu_read_lock();
+ idev = __in_dev_get_rcu(bp->dev);
+ if (idev)
+ ifa = rcu_dereference(idev->ifa_list);
+ if (!ifa) {
+ rcu_read_unlock();
+ netdev_err(netdev, "IP address not assigned as required by WoL walk ARP\n");
+ return -EOPNOTSUPP;
+ }
+ ifa_local = be32_to_cpu(ifa->ifa_local);
+ rcu_read_unlock();
}
+
spin_lock_irqsave(&bp->lock, flags);

/* Disable Tx and Rx engines before disabling the queues,
@@ -5830,7 +5837,7 @@ static int __maybe_unused macb_suspend(s
if (bp->wolopts & WAKE_ARP) {
tmp |= MACB_BIT(ARP);
/* write IP address into register */
- tmp |= MACB_BFEXT(IP, be32_to_cpu(ifa->ifa_local));
+ tmp |= MACB_BFEXT(IP, ifa_local);
}
spin_unlock_irqrestore(&bp->lock, flags);