[PATCH v2] Linux: Also check for 0 return value from vDSO gerandom probe

[Florian Weimer]

* Florian Weimer:

> As of Linux 6.13, there is no code in the vDSO that declines this
> initialization request with the special ~0UL state size.  If the vDSO
> has the function, the call succeeds and returns 0.  It's expected
> that the code would follow the “a negative value indicating an error”
> convention, as indicated in the __cvdso_getrandom_data function
> comment, so that INTERNAL_SYSCALL_ERROR_P on glibc's side would return
> true. This commit changes the commit to check for zero to indicate
> success instead, which covers potential future non-zero success
> return values and error returns.
>
> Fixes commit 4f5704ea347e52ac3f272d1341da10aed6e9973e ("powerpc: Use
> correct procedure call standard for getrandom vDSO call (bug 32440)").
>
> Tested on x86_64-linux-gnu.

I changed the commit subject to:

Linux: Check for 0 return value from vDSO getrandom probe

(typo fix, and reflecting the ret == 0 check)

Thanks,
Florian