[PATCH 6.6 069/160] hwmon: (tps53679) Fix device ID comparison and printing in tps53676_identify()

Greg Kroah-Hartman
2026-04-08T18:24:45Z

From: Sanman Pradhan <psanman@juniper.net>

[ Upstream commit ca34ee6d0307a0b4e52c870dfc1bb8a3c3eb956e ]

tps53676_identify() uses strncmp() to compare the device ID buffer
against a byte sequence containing embedded non-printable bytes
(\x53\x67\x60). strncmp() is semantically wrong for binary data
comparison; use memcmp() instead.

Additionally, the buffer from i2c_smbus_read_block_data() is not
NUL-terminated, so printing it with "%s" in the error path is
undefined behavior and may read past the buffer. Use "%*ph" to
hex-dump the actual bytes returned.

Per the datasheet, the expected device ID is the 6-byte sequence
54 49 53 67 60 00 ("TI\x53\x67\x60\x00"), so compare all 6 bytes
including the trailing NUL.

Fixes: cb3d37b59012 ("hwmon: (pmbus/tps53679) Add support for TI TPS53676")
Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Link: https://lore.kernel.org/r/20260330155618.77403-1-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/pmbus/tps53679.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/pmbus/tps53679.c b/drivers/hwmon/pmbus/tps53679.c
index 5c9466244d70d..ecc1be33b3b1b 100644
--- a/drivers/hwmon/pmbus/tps53679.c
+++ b/drivers/hwmon/pmbus/tps53679.c
@@ -156,8 +156,8 @@ static int tps53676_identify(struct i2c_client *client,
ret = i2c_smbus_read_block_data(client, PMBUS_IC_DEVICE_ID, buf);
if (ret < 0)
return ret;
- if (strncmp("TI\x53\x67\x60", buf, 5)) {
- dev_err(&client->dev, "Unexpected device ID: %s\n", buf);
+ if (ret != 6 || memcmp(buf, "TI\x53\x67\x60\x00", 6)) {
+ dev_err(&client->dev, "Unexpected device ID: %*ph\n", ret, buf);
return -ENODEV;
}

--
2.53.0