Subject: Coverity: degc_to_code(): Integer handling issues

From: coverity-bot <[email-masked]>
Date: Mon, 28 Oct 2019 16:06:23 -0700

Hello!

This is an experimental automated report about issues detected by Coverity
from a scan of next-20191025 as part of the linux-next weekly scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified
lines of code (noted below) that were touched by recent commits:

fbfe1a042cfd ("drivers: thermal: tsens: Add interrupt support")

Coverity reported the following:

*** CID 1487360:  Integer handling issues  (OVERFLOW_BEFORE_WIDEN)
/drivers/thermal/qcom/tsens-common.c: 95 in degc_to_code()
89     		dev_dbg(priv->dev, "%s: offset:%d\n", __func__, priv->sensor[i].offset);
90     	}
91     }
92
93     static inline u32 degc_to_code(int degc, const struct tsens_sensor *s)
94     {
vvv     CID 1487360:  Integer handling issues  (OVERFLOW_BEFORE_WIDEN)
vvv     Potentially overflowing expression "degc * s->slope" with type "int" (32 bits, signed) is evaluated using 32-bit arithmetic, and then used in a context that expects an expression of type "u64" (64 bits, unsigned).
95     	u64 code = (degc * s->slope + s->offset) / SLOPE_FACTOR;
96
97     	pr_debug("%s: raw_code: 0x%llx, degc:%d\n", __func__, code, degc);
98     	return clamp_val(code, THRESHOLD_MIN_ADC_CODE, THRESHOLD_MAX_ADC_CODE);
99     }
100

If this is a false positive, please let us know so we can mark it as
such, or teach the Coverity rules to be smarter. If not, please make
sure fixes get into linux-next. :) For patches fixing this, please
include:

Reported-by: coverity-bot <[email-masked]>
Addresses-Coverity-ID: 1487360 ("Integer handling issues")
Fixes: fbfe1a042cfd ("drivers: thermal: tsens: Add interrupt support")

Thanks for your attention!

-- 
Coverity-bot