From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Jiawen Wu <jiawenwu@trustnetic.com>,
	Breno Leitao <leitao@debian.org>,
	Simon Horman <horms@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18 192/217] net: ngbe: fix NULL pointer dereference in non-MSI-X interrupt enabling
Date: Thu, 20 Aug 2026 16:56:00 +0200
Message-ID: <20260820145243.494853715@linuxfoundation.org>
In-Reply-To: <20260820145237.531699751@linuxfoundation.org>
References: <20260820145237.531699751@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

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

From: Jiawen Wu <jiawenwu@trustnetic.com>

[ Upstream commit 5f3a13e0bb5ebcc1ca2dfda42ea40b9f3c2be6ea ]

In non-MSI-X mode (such as legacy INTx or single MSI), wx->msix_entry is
not allocated or initialized. Calling NGBE_INTR_MISC(wx) dereferences
wx->msix_entry->entry, leading to a NULL pointer dereference crash.

This issue was introduced by fixing the IRQ vector when the number of
VFs is 7. Fix the issue by explicitly checking `pdev->msix_enabled` to
determine the correct vector index.

Additionally, as a side fix, set the interrupt mask to BIT(0) for the
non-MSI-X fallback. In MSI/INTx mode, the MISC and queue interrupts
share vector 0, and the WX_PX_MISC_IVAR register is only valid in the
MSI-X case. Thus, BIT(0) is the correct mask for the miscellaneous cause
when MSI-X is disabled.

Fixes: 4174c0c331a2 ("net: ngbe: specify IRQ vector when the number of VFs is 7")
Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/B2693E9A8BFAD110+20260807062214.410838-1-jiawenwu@trustnetic.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/wangxun/ngbe/ngbe_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/wangxun/ngbe/ngbe_main.c b/drivers/net/ethernet/wangxun/ngbe/ngbe_main.c
index 58488e138beb4..e80962d40f7ed 100644
--- a/drivers/net/ethernet/wangxun/ngbe/ngbe_main.c
+++ b/drivers/net/ethernet/wangxun/ngbe/ngbe_main.c
@@ -160,8 +160,10 @@ static void ngbe_irq_enable(struct wx *wx, bool queues)
 	/* mask interrupt */
 	if (queues)
 		wx_intr_enable(wx, NGBE_INTR_ALL);
-	else
+	else if (wx->pdev->msix_enabled)
 		wx_intr_enable(wx, NGBE_INTR_MISC(wx));
+	else
+		wx_intr_enable(wx, BIT(0));
 }
 
 /**
-- 
2.53.0