From 43cae21424ff8e33894a0f86c6b80b840c049fd7 Mon Sep 17 00:00:00 2001 From: Abdurrahman Hussain Date: Fri, 15 May 2026 15:11:51 -0700 Subject: [PATCH] hwmon: (pmbus/adm1266) bounce blackbox records through a protocol-sized buffer adm1266_pmbus_block_xfer() copies the device-supplied block payload into the caller-provided buffer using the device-supplied length: memcpy(data_r, &msgs[1].buf[1], msgs[1].buf[0]); The helper does not know how large data_r is and trusts the device to return at most one record's worth of bytes. adm1266_nvmem_read_blackbox() violates that contract: it advances read_buff inside data->dev_mem in ADM1266_BLACKBOX_SIZE (64-byte) strides while the helper is willing to write up to ADM1266_PMBUS_BLOCK_MAX (255) bytes. A device that returns more than 64 bytes on the trailing record (read_buff offset 1984 in the 2048-byte dev_mem allocation) overflows dev_mem by up to 191 bytes before the post-call if (ret != ADM1266_BLACKBOX_SIZE) return -EIO; can reject the response. Contain the fix in the caller without changing the helper signature: read each record into a 255-byte local bounce buffer that matches the helper's maximum output, validate the returned length, and only then copy exactly ADM1266_BLACKBOX_SIZE bytes into the dev_mem slot. Fixes: 407dc802a9c0 ("hwmon: (pmbus/adm1266) Add Block process call") Cc: stable@vger.kernel.org Signed-off-by: Abdurrahman Hussain Link: https://lore.kernel.org/r/20260515-adm1266-fixes-v1-5-1c1ea1349cfe@nexthop.ai Signed-off-by: Guenter Roeck --- drivers/hwmon/pmbus/adm1266.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm1266.c index 9820dc9e1f2e..1fcd86ee96fe 100644 --- a/drivers/hwmon/pmbus/adm1266.c +++ b/drivers/hwmon/pmbus/adm1266.c @@ -349,6 +349,7 @@ static void adm1266_init_debugfs(struct adm1266_data *data) static int adm1266_nvmem_read_blackbox(struct adm1266_data *data, u8 *read_buff) { + u8 record[ADM1266_PMBUS_BLOCK_MAX]; int record_count; char index; u8 buf[I2C_SMBUS_BLOCK_MAX]; @@ -366,13 +367,14 @@ static int adm1266_nvmem_read_blackbox(struct adm1266_data *data, u8 *read_buff) return -EIO; for (index = 0; index < record_count; index++) { - ret = adm1266_pmbus_block_xfer(data, ADM1266_READ_BLACKBOX, 1, &index, read_buff); + ret = adm1266_pmbus_block_xfer(data, ADM1266_READ_BLACKBOX, 1, &index, record); if (ret < 0) return ret; if (ret != ADM1266_BLACKBOX_SIZE) return -EIO; + memcpy(read_buff, record, ADM1266_BLACKBOX_SIZE); read_buff += ADM1266_BLACKBOX_SIZE; }