From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Li RongQing <lirongqing@baidu.com>,
	"Anirudh Rayabharam (Microsoft)" <anirudh@anirudhrb.com>,
	Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>,
	Wei Liu <wei.liu@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18 585/641] mshv: fix SRCU protection in irqfd resampler ack handler
Date: Tue, 24 Feb 2026 17:25:11 -0800
Message-ID: <20260225012402.687400161@linuxfoundation.org>
In-Reply-To: <20260225012348.915798704@linuxfoundation.org>
References: <20260225012348.915798704@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Li RongQing <lirongqing@baidu.com>

[ Upstream commit 2e7577cd5ddc1f86d1b6c48caf3cfa87dbb14e34 ]

Replace hlist_for_each_entry_rcu() with hlist_for_each_entry_srcu()
in mshv_irqfd_resampler_ack() to correctly handle SRCU-protected
linked list traversal.

The function uses SRCU (sleepable RCU) synchronization via
partition->pt_irq_srcu, but was incorrectly using the RCU variant
for list iteration. This could lead to race conditions when the
list is modified concurrently.

Also add srcu_read_lock_held() assertion as required by
hlist_for_each_entry_srcu() to ensure we're in the proper
read-side critical section.

Fixes: 621191d709b14 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Acked-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hv/mshv_eventfd.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/mshv_eventfd.c b/drivers/hv/mshv_eventfd.c
index 806674722868b..05d643f54f45a 100644
--- a/drivers/hv/mshv_eventfd.c
+++ b/drivers/hv/mshv_eventfd.c
@@ -87,8 +87,9 @@ static void mshv_irqfd_resampler_ack(struct mshv_irq_ack_notifier *mian)
 
 	idx = srcu_read_lock(&partition->pt_irq_srcu);
 
-	hlist_for_each_entry_rcu(irqfd, &resampler->rsmplr_irqfd_list,
-				 irqfd_resampler_hnode) {
+	hlist_for_each_entry_srcu(irqfd, &resampler->rsmplr_irqfd_list,
+				 irqfd_resampler_hnode,
+				 srcu_read_lock_held(&partition->pt_irq_srcu)) {
 		if (hv_should_clear_interrupt(irqfd->irqfd_lapic_irq.lapic_control.interrupt_type))
 			hv_call_clear_virtual_interrupt(partition->pt_id);
 
-- 
2.51.0