linux-kernel - [PATCH 1/1] i2c: designware: Disable SMBus interrupts to prevent storms from mis-configured firmware

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20251011073057.2959-2-guojinhui.liam@bytedance.com>
Date: Sat, 11 Oct 2025 15:30:57 +0800
From: Jinhui Guo <guojinhui.liam@...edance.com>
To: mika.westerberg@...ux.intel.com,
	andriy.shevchenko@...ux.intel.com,
	jsd@...ihalf.com,
	andi.shyti@...nel.org
Cc: guojinhui.liam@...edance.com,
	linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] i2c: designware: Disable SMBus interrupts to prevent storms from mis-configured firmware

When probing the I2C master, disable SMBus interrupts to prevent
storms caused by broken firmware mis-configuring IC_SMBUS=1; the
handler never services them and a mis-configured SMBUS Master
extend-clock timeout can flood the CPU.

Signed-off-by: Jinhui Guo <guojinhui.liam@...edance.com>
---
 drivers/i2c/busses/i2c-designware-core.h   |  1 +
 drivers/i2c/busses/i2c-designware-master.c | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 347843b4f5dd..d1122ff0a1b7 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -78,6 +78,7 @@
 #define DW_IC_TX_ABRT_SOURCE			0x80
 #define DW_IC_ENABLE_STATUS			0x9c
 #define DW_IC_CLR_RESTART_DET			0xa8
+#define DW_IC_SMBUS_INTR_MASK		0xcc
 #define DW_IC_COMP_PARAM_1			0xf4
 #define DW_IC_COMP_VERSION			0xf8
 #define DW_IC_SDA_HOLD_MIN_VERS			0x3131312A /* "111*" == v1.11* */
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index c7a72c28786c..eeb60536da32 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -997,6 +997,11 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 	return 0;
 }
 
+static inline void i2c_dw_disable_smbus_intr(struct dw_i2c_dev *dev)
+{
+	regmap_write(dev->map, DW_IC_SMBUS_INTR_MASK, 0);
+}
+
 int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 {
 	struct i2c_adapter *adap = &dev->adapter;
@@ -1063,6 +1068,12 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 		return ret;
 
 	__i2c_dw_write_intr_mask(dev, 0);
+	/*
+	 * Mask SMBus interrupts to block storms from broken
+	 * firmware that leaves IC_SMBUS=1; the handler never
+	 * services them.
+	 */
+	i2c_dw_disable_smbus_intr(dev);
 	i2c_dw_release_lock(dev);
 
 	if (!(dev->flags & ACCESS_POLLING)) {
-- 
2.20.1