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Re: [Qemu-devel] [PULL 10/25] util: Add qemu_guest_getrandom and associa
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PULL 10/25] util: Add qemu_guest_getrandom and associated routines |
Date: |
Thu, 30 May 2019 14:45:33 +0100 |
On Thu, 30 May 2019 at 14:41, Richard Henderson
<address@hidden> wrote:
>
> On 5/30/19 6:29 AM, Peter Maydell wrote:
> > On Wed, 22 May 2019 at 19:42, Richard Henderson
> > <address@hidden> wrote:
> >>
> >> This routine is intended to produce high-quality random numbers to the
> >> guest. Normally, such numbers are crypto quality from the host, but a
> >> command-line option can force the use of a fully deterministic sequence
> >> for use while debugging.
> >
> >> +void qemu_guest_getrandom_nofail(void *buf, size_t len)
> >> +{
> >> + qemu_guest_getrandom(buf, len, &error_fatal);
> >> +}
> >>
> >
> > Hi; Coverity complains about this because in the other 4 places
> > where we call qemu_guest_getrandom() we check its return
> > value, but here we ignore it. If qemu_guest_getrandom() can't
> > fail ever then we don't need the separate _nofail() version.
> > If it can fail sometimes but not here then we should assert()
> > so with a comment explaining why it can't fail, or we should
> > do an error-exit check like qdev_init_nofail().
> > (This is CID 1401701.)
>
> Because of &error_fatal, we will have already exited on error. As a qapi
> programming pattern, that seems clear in this context.
Whoops, I didn't see the error_fatal. I think that a cast to void
will indeed silence the Coverity error (at least a quick google
search suggests it will).
thanks
-- PMM
- [Qemu-devel] [PULL 24/25] target/ppc: Use qemu_guest_getrandom for DARN, (continued)
- [Qemu-devel] [PULL 24/25] target/ppc: Use qemu_guest_getrandom for DARN, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 20/25] hw/misc/exynos4210_rng: Use qemu_guest_getrandom, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 21/25] target/arm: Put all PAC keys into a structure, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 18/25] hw/misc/nrf51_rng: Use qemu_guest_getrandom_nofail, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 14/25] linux-user: Use qemu_guest_getrandom_nofail for AT_RANDOM, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 13/25] linux-user: Call qcrypto_init if not using -seed, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 12/25] linux-user: Initialize pseudo-random seeds for all guest cpus, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 10/25] util: Add qemu_guest_getrandom and associated routines, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 07/25] crypto: Change the qcrypto_random_bytes buffer type to void*, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 02/25] build: Link user-only with crypto random number objects, Richard Henderson, 2019/05/22
- [Qemu-devel] [PULL 01/25] configure: Link test before auto-enabling crypto libraries, Richard Henderson, 2019/05/22
- Re: [Qemu-devel] [PULL 00/25] Add qemu_getrandom and ARMv8.5-RNG etc, Peter Maydell, 2019/05/23