FAILED: patch "[PATCH] hwmon: (pmbus/adm1266) serialize NVMEM blackbox read with" failed to apply to 7.0-stable tree

The patch below does not apply to the 7.0-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-7.0.y
git checkout FETCH_HEAD
git cherry-pick -x 9f1dd8f9491eb840cbea7ffdf4cad031e25f8ae0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026052829-nutshell-shank-d239@gregkh' --subject-prefix 'PATCH 7.0.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9f1dd8f9491eb840cbea7ffdf4cad031e25f8ae0 Mon Sep 17 00:00:00 2001
From: Abdurrahman Hussain <[email protected]>
Date: Mon, 18 May 2026 17:52:31 -0700
Subject: [PATCH] hwmon: (pmbus/adm1266) serialize NVMEM blackbox read with
pmbus_lock

adm1266_nvmem_read() is the reg_read callback the NVMEM core invokes when userspace reads /sys/bus/nvmem/devices/.../nvmem on this chip. On the first byte of every read it does a memset of data->dev_mem, walks the device blackbox through adm1266_nvmem_read_blackbox() (which issues a chain of PMBus block transactions), and then memcpys the refreshed buffer out to userspace. None of that runs under pmbus_lock today.

Two consequences:

- The PMBus traffic the refresh issues is not serialised against pmbus_core's own multi-step PAGE+register sequences. A paged hwmon attribute read from another thread can land between a PAGE write and the paged read in either direction and corrupt one side's view of the device state machine.

- The NVMEM core does not serialise concurrent reg_read calls, so two userspace readers racing at offset 0 can interleave the memset of data->dev_mem with another reader's adm1266_nvmem_read_blackbox() refill or memcpy out, returning torn data to userspace.

Take pmbus_lock at the top of adm1266_nvmem_read() via the scope-based guard(). Patch 5 of this series moves adm1266_config_nvmem() past pmbus_do_probe() so the lock is guaranteed to be live before the callback is reachable from userspace.

index 0eef58dd69a6..5ddca5701032 100644
@@ -400,6 +400,8 @@ static int adm1266_nvmem_read(void *priv, unsigned int offset, void *val, size_t
 	if (offset + bytes > data->nvmem_config.size)
 		return -EINVAL;
 
+	guard(pmbus_lock)(data->client);
+
 	if (offset == 0) {
 		memset(data->dev_mem, 0, data->nvmem_config.size);
 

From: Guenter Roeck <[email protected]>

[ Upstream commit 1814f4d3ff358277a5b6957e7f133c2812dc80ec ]

Add support for guard(pmbus_lock)() and scoped_guard(pmbus_lock)() to be able to simplify the PMBus code.

Also introduce pmbus_lock() as pre-requisite for supporting guard().

Stable-dep-of: 9f1dd8f9491e ("hwmon: (pmbus/adm1266) serialize NVMEM blackbox read with pmbus_lock")

---
 drivers/hwmon/pmbus/pmbus.h      | 5 +++++
 drivers/hwmon/pmbus/pmbus_core.c | 8 ++++++++
 2 files changed, 13 insertions(+)

index d2e9bfb5320fc..e499cdae9442c 100644
@@ -10,6 +10,7 @@
 #define PMBUS_H
 
 #include <linux/bitops.h>
+#include <linux/cleanup.h>
 #include <linux/regulator/driver.h>
 
 /*

@@ -563,7 +564,11 @@ int pmbus_get_fan_rate_device(struct i2c_client *client, int page, int id,
 int pmbus_get_fan_rate_cached(struct i2c_client *client, int page, int id,
 			      enum pmbus_fan_mode mode);
 int pmbus_lock_interruptible(struct i2c_client *client);
+void pmbus_lock(struct i2c_client *client);
 void pmbus_unlock(struct i2c_client *client);
+
+DEFINE_GUARD(pmbus_lock, struct i2c_client *, pmbus_lock(_T), pmbus_unlock(_T))
+
 int pmbus_update_fan(struct i2c_client *client, int page, int id,
 		     u8 config, u8 mask, u16 command);
 struct dentry *pmbus_get_debugfs_dir(struct i2c_client *client);

index 572be3ebc03df..7150f12d26300 100644
@@ -3871,6 +3871,14 @@ struct dentry *pmbus_get_debugfs_dir(struct i2c_client *client)
 }
 EXPORT_SYMBOL_NS_GPL(pmbus_get_debugfs_dir, "PMBUS");
 
+void pmbus_lock(struct i2c_client *client)
+{
+	struct pmbus_data *data = i2c_get_clientdata(client);
+
+	mutex_lock(&data->update_lock);
+}
+EXPORT_SYMBOL_NS_GPL(pmbus_lock, "PMBUS");
+
 int pmbus_lock_interruptible(struct i2c_client *client)
 {
 	struct pmbus_data *data = i2c_get_clientdata(client);

2.53.0

From: Abdurrahman Hussain <[email protected]>

[ Upstream commit 9f1dd8f9491eb840cbea7ffdf4cad031e25f8ae0 ]

adm1266_nvmem_read() is the reg_read callback the NVMEM core invokes when userspace reads /sys/bus/nvmem/devices/.../nvmem on this chip. On the first byte of every read it does a memset of data->dev_mem, walks the device blackbox through adm1266_nvmem_read_blackbox() (which issues a chain of PMBus block transactions), and then memcpys the refreshed buffer out to userspace. None of that runs under pmbus_lock today.

Two consequences:

- The PMBus traffic the refresh issues is not serialised against pmbus_core's own multi-step PAGE+register sequences. A paged hwmon attribute read from another thread can land between a PAGE write and the paged read in either direction and corrupt one side's view of the device state machine.

- The NVMEM core does not serialise concurrent reg_read calls, so two userspace readers racing at offset 0 can interleave the memset of data->dev_mem with another reader's adm1266_nvmem_read_blackbox() refill or memcpy out, returning torn data to userspace.

Take pmbus_lock at the top of adm1266_nvmem_read() via the scope-based guard(). Patch 5 of this series moves adm1266_config_nvmem() past pmbus_do_probe() so the lock is guaranteed to be live before the callback is reachable from userspace.

---
 drivers/hwmon/pmbus/adm1266.c | 2 ++
 1 file changed, 2 insertions(+)

index d90f8f80be8e0..3efa704410538 100644
@@ -383,6 +383,8 @@ static int adm1266_nvmem_read(void *priv, unsigned int offset, void *val, size_t
 	if (offset + bytes > data->nvmem_config.size)
 		return -EINVAL;
 
+	guard(pmbus_lock)(data->client);
+
 	if (offset == 0) {
 		memset(data->dev_mem, 0, data->nvmem_config.size);
 

2.53.0

From: Guenter Roeck <[email protected]>

[ Upstream commit 1814f4d3ff358277a5b6957e7f133c2812dc80ec ]

Add support for guard(pmbus_lock)() and scoped_guard(pmbus_lock)() to be able to simplify the PMBus code.

Also introduce pmbus_lock() as pre-requisite for supporting guard().

Stable-dep-of: 9f1dd8f9491e ("hwmon: (pmbus/adm1266) serialize NVMEM blackbox read with pmbus_lock")

---
 drivers/hwmon/pmbus/pmbus.h      | 5 +++++
 drivers/hwmon/pmbus/pmbus_core.c | 8 ++++++++
 2 files changed, 13 insertions(+)

index d2e9bfb5320fc..e499cdae9442c 100644
@@ -10,6 +10,7 @@
 #define PMBUS_H
 
 #include <linux/bitops.h>
+#include <linux/cleanup.h>
 #include <linux/regulator/driver.h>
 
 /*

@@ -563,7 +564,11 @@ int pmbus_get_fan_rate_device(struct i2c_client *client, int page, int id,
 int pmbus_get_fan_rate_cached(struct i2c_client *client, int page, int id,
 			      enum pmbus_fan_mode mode);
 int pmbus_lock_interruptible(struct i2c_client *client);
+void pmbus_lock(struct i2c_client *client);
 void pmbus_unlock(struct i2c_client *client);
+
+DEFINE_GUARD(pmbus_lock, struct i2c_client *, pmbus_lock(_T), pmbus_unlock(_T))
+
 int pmbus_update_fan(struct i2c_client *client, int page, int id,
 		     u8 config, u8 mask, u16 command);
 struct dentry *pmbus_get_debugfs_dir(struct i2c_client *client);

index 572be3ebc03df..7150f12d26300 100644
@@ -3871,6 +3871,14 @@ struct dentry *pmbus_get_debugfs_dir(struct i2c_client *client)
 }
 EXPORT_SYMBOL_NS_GPL(pmbus_get_debugfs_dir, "PMBUS");
 
+void pmbus_lock(struct i2c_client *client)
+{
+	struct pmbus_data *data = i2c_get_clientdata(client);
+
+	mutex_lock(&data->update_lock);
+}
+EXPORT_SYMBOL_NS_GPL(pmbus_lock, "PMBUS");
+
 int pmbus_lock_interruptible(struct i2c_client *client)
 {
 	struct pmbus_data *data = i2c_get_clientdata(client);

2.53.0

From: Abdurrahman Hussain <[email protected]>

[ Upstream commit 9f1dd8f9491eb840cbea7ffdf4cad031e25f8ae0 ]

adm1266_nvmem_read() is the reg_read callback the NVMEM core invokes when userspace reads /sys/bus/nvmem/devices/.../nvmem on this chip. On the first byte of every read it does a memset of data->dev_mem, walks the device blackbox through adm1266_nvmem_read_blackbox() (which issues a chain of PMBus block transactions), and then memcpys the refreshed buffer out to userspace. None of that runs under pmbus_lock today.

Two consequences:

- The PMBus traffic the refresh issues is not serialised against pmbus_core's own multi-step PAGE+register sequences. A paged hwmon attribute read from another thread can land between a PAGE write and the paged read in either direction and corrupt one side's view of the device state machine.

- The NVMEM core does not serialise concurrent reg_read calls, so two userspace readers racing at offset 0 can interleave the memset of data->dev_mem with another reader's adm1266_nvmem_read_blackbox() refill or memcpy out, returning torn data to userspace.

Take pmbus_lock at the top of adm1266_nvmem_read() via the scope-based guard(). Patch 5 of this series moves adm1266_config_nvmem() past pmbus_do_probe() so the lock is guaranteed to be live before the callback is reachable from userspace.

---
 drivers/hwmon/pmbus/adm1266.c | 2 ++
 1 file changed, 2 insertions(+)

index d90f8f80be8e0..3efa704410538 100644
@@ -383,6 +383,8 @@ static int adm1266_nvmem_read(void *priv, unsigned int offset, void *val, size_t
 	if (offset + bytes > data->nvmem_config.size)
 		return -EINVAL;
 
+	guard(pmbus_lock)(data->client);
+
 	if (offset == 0) {
 		memset(data->dev_mem, 0, data->nvmem_config.size);
 

2.53.0