From: Sanman Pradhan Date: Thu, 19 Mar 2026 17:31:29 +0000 (+0000) Subject: hwmon: (pmbus/isl68137) Add mutex protection for AVS enable sysfs attributes X-Git-Tag: v7.0-rc6~17^2~6 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3075a3951f7708da5a8ab47b0b7d068a32f69e58;p=thirdparty%2Fkernel%2Flinux.git hwmon: (pmbus/isl68137) Add mutex protection for AVS enable sysfs attributes The custom avs0_enable and avs1_enable sysfs attributes access PMBus registers through the exported API helpers (pmbus_read_byte_data, pmbus_read_word_data, pmbus_write_word_data, pmbus_update_byte_data) without holding the PMBus update_lock mutex. These exported helpers do not acquire the mutex internally, unlike the core's internal callers which hold the lock before invoking them. The store callback is especially vulnerable: it performs a multi-step read-modify-write sequence (read VOUT_COMMAND, write VOUT_COMMAND, then update OPERATION) where concurrent access from another thread could interleave and corrupt the register state. Add pmbus_lock_interruptible()/pmbus_unlock() around both the show and store callbacks to serialize PMBus register access with the rest of the driver. Fixes: 038a9c3d1e424 ("hwmon: (pmbus/isl68137) Add driver for Intersil ISL68137 PWM Controller") Cc: stable@vger.kernel.org Signed-off-by: Sanman Pradhan Link: https://lore.kernel.org/r/20260319173055.125271-3-sanman.pradhan@hpe.com Signed-off-by: Guenter Roeck --- diff --git a/drivers/hwmon/pmbus/isl68137.c b/drivers/hwmon/pmbus/isl68137.c index e7dac26b5be6..3e3a887aad05 100644 --- a/drivers/hwmon/pmbus/isl68137.c +++ b/drivers/hwmon/pmbus/isl68137.c @@ -96,7 +96,15 @@ static ssize_t isl68137_avs_enable_show_page(struct i2c_client *client, int page, char *buf) { - int val = pmbus_read_byte_data(client, page, PMBUS_OPERATION); + int val; + + val = pmbus_lock_interruptible(client); + if (val) + return val; + + val = pmbus_read_byte_data(client, page, PMBUS_OPERATION); + + pmbus_unlock(client); if (val < 0) return val; @@ -118,6 +126,10 @@ static ssize_t isl68137_avs_enable_store_page(struct i2c_client *client, op_val = result ? ISL68137_VOUT_AVS : 0; + rc = pmbus_lock_interruptible(client); + if (rc) + return rc; + /* * Writes to VOUT setpoint over AVSBus will persist after the VRM is * switched to PMBus control. Switching back to AVSBus control @@ -129,17 +141,20 @@ static ssize_t isl68137_avs_enable_store_page(struct i2c_client *client, rc = pmbus_read_word_data(client, page, 0xff, PMBUS_VOUT_COMMAND); if (rc < 0) - return rc; + goto unlock; rc = pmbus_write_word_data(client, page, PMBUS_VOUT_COMMAND, rc); if (rc < 0) - return rc; + goto unlock; } rc = pmbus_update_byte_data(client, page, PMBUS_OPERATION, ISL68137_VOUT_AVS, op_val); +unlock: + pmbus_unlock(client); + return (rc < 0) ? rc : count; }