hwmon: adm1275: Prevent reading uninitialized stack

Overview

In the Linux kernel, the following vulnerability has been resolved:

hwmon: adm1275: Prevent reading uninitialized stack

While adding support for the ROHM BD127X0 hot-swap controllers, sashiko reported an error in device-name comparison, which can lead to reading uninitialized stack memory.

Quoting Sashiko:

This is a pre-existing issue, but I noticed that just before this block in adm1275_probe(), there might be an out-of-bounds stack read:

ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
if (ret < 0) { ... }
for (mid = adm1275_id; mid->name[0]; mid++) {
        if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))
                break;
}

Since i2c_smbus_read_block_data() reads up to 32 bytes into the uninitialized stack array block_buffer without appending a null terminator, strncasecmp() could read past the valid bytes returned in ret.

For example, if the device returns a shorter string like "adm12", checking it against "adm1275" up to the length of "adm1275" will continue reading into uninitialized stack bounds.

Prevent reading uninitialized memory by zeroing the stack array.

Affected

• Linux >= 87102808d03948c825c3bdc48316e48f6422fd7e < 57d583f069fa9d3d0c0831e34b967d1f61edae94
• Linux >= 87102808d03948c825c3bdc48316e48f6422fd7e < 82e4ab03a6ab9b87667410f5143bc484d7a62bdc
• Linux >= 87102808d03948c825c3bdc48316e48f6422fd7e < c9e04a52663bc6651c06c2427df088b751062bd6
• Linux >= 87102808d03948c825c3bdc48316e48f6422fd7e < 39a581bd64a0e91112ec8017a2dd4e70c1336e99
• Linux >= 87102808d03948c825c3bdc48316e48f6422fd7e < aa35cee30686e6be3c890bf741429c5025d55abe
• Linux >= 87102808d03948c825c3bdc48316e48f6422fd7e < 36554592e2f5cac16ff8bf73720d38a6d9ef4a20
• Linux >= 87102808d03948c825c3bdc48316e48f6422fd7e < 93b96e723bdcba6172a5814262be875abcc5d269
• Linux >= 87102808d03948c825c3bdc48316e48f6422fd7e < 553f9517813912a5ab661af5504485d96824a61c
• Linux 3.3

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.