[Coverity CID :195793]Insecure data handling in /drivers/counter/counter_ll_stm32_rtc.c

[aasthagr]

Static code scan issues seen in File: /drivers/counter/counter_ll_stm32_rtc.c
Category: Insecure data handling
Function: rtc_stm32_read
Component: Drivers
CID: 195793
Please fix or provide comments to square it off in coverity in the link: https://scan9.coverity.com/reports.htm#v32951/p12996

[erwango]

@galak, coverity complains on :

	time_t ts;
...
	ticks = counter_us_to_ticks(dev, (u64_t)(ts * USEC_PER_SEC));

With following comment:

CID 195871 (#1 of 1): Unintentional integer overflow 
(OVERFLOW_BEFORE_WIDEN)overflow_before_widen: Potentially overflowing expression ts * 
1000000UL with type unsigned long (32 bits, unsigned) is evaluated using 32-bit arithmetic,
and  then used in a context that expects an expression of type u64_t (64 bits, unsigned).
   To avoid overflow, cast either ts or 1000000UL to type u64_t rather than casting
 the result of the potential overflow.

But, sizeof(time_t) returns 8...

So actually this piece of code doesn't work anymore (it used to), and I need to cast ts on u32_t to get it back working. Is that possible time_t has changes from 4 to 8 bytes recently?

[GeorgeCGV]

For me with newlibc (required by stm32 rtc driver) with arm none eabi 7-2017-q4-major toolchain sizeof types u32_t, s32_t, and time_t are all 4 bytes.

[erwango]

with arm none eabi 7-2017-q4-major toolchain sizeof types u32_t, s32_t, and time_t are all 4 bytes

On my side, I'm using SDK0.10.0

[erwango]

Coverity analysis assumes time_t is 4 bytes while it has been updated to 8 bytes with SDK0.10.0.
Report does not apply anymore with 8 byte time_t, so issue will be fixed by upgrading SDK to 0.10.0 at next run.
I'm not able to update coverity report with this anlaysis (rights issue?), @aasthagr can you do it?

[GeorgeCGV]

newlib time_t has been changed to signed 64 bits integer by default in commit 4de8754bac676fc7f29082ccf8281b1c73ce629e back in September 2017.

SDK 0.10.0 uses newlib 3.1.0.
And, as it seems from the release notes, amr none eabi 7-2017-q4-major shall already include the newlib with the 64 bits time_t (but not in versions prior 7-2017-q4-major).