Messages in this thread | | | Subject | Re: nct6775: UBSAN: shift exponent 32 is too large for 32-bit type 'long unsigned int' | From | Paul Menzel <> | Date | Wed, 13 Jun 2018 08:57:58 +0200 |
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Dear Guenter,
Am 13.06.2018 um 00:12 schrieb Guenter Roeck:
> On Tue, Jun 12, 2018 at 11:50:45PM +0200, Paul Menzel wrote:
>> Building Linux with the undefined behavior sanitizer (UBSAN), loading the >> module *nct6775* on the ASRock E350M1 shows the error below. >> >> ``` >> [ 28.322775] UBSAN: Undefined behaviour in drivers/hwmon/nct6775.c:4179:27 >> [ 28.322833] shift exponent 32 is too large for 32-bit type 'long unsigned int' >> ``` >> >> I believe this was introduced by commit cc66b3038254 (hwmon: (nct6775) >> Rework temperature source and label handling), but the same issue was >> already present before. > > I don't think so. The code used to be > for (i = 0; i < data->temp_label_num - 1; i++) { > Notice the "- 1". So it should be > for (i = 0; i < 31; i++) { > > In practice it doesn't matter because "data->temp_mask & BIT(31 + 1)" > will always be false, causing the last loop iteration to abort, but > it is nevertheless wrong. > > Thanks a lot for the report. I'll prepare a patch.
Thank you for the instant response. I tested your proposed change, and, as expected, the error is gone.
Kind regards,
Paul
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