On Mon, Oct 14, 2019 at 01:51:39PM +0100, Peter Maydell wrote: > On Fri, 4 Oct 2019 at 04:10, David Gibson <da...@gibson.dropbear.id.au> wrote: > > > > exynos4210_gic_realize() prints the number of cpus into some temporary > > buffers, but it only allows 3 bytes space for it. That's plenty - I'm > > pretty sure that existing machines will only ever set this value to 2 > > (EXYNOS4210_NCPUS). But the compiler can't really be expected to figure > > that out. > > > > Some[*] gcc9 versions therefore emit -Wformat-truncation warnings. Fix > > that by allowing more space in the temporary buffers - these are on stack > > very briefly before being essentially strdup()ed inside the memory region > > code, so there's not much cost to doing so. > > > > [*] The bizarre thing here, is that I've long gotten these warnings > > compiling in a 32-bit x86 container as host - Fedora 30 with > > gcc-9.2.1-1.fc30.i686 - but it compiles just fine on my normal x86_64 host > > - Fedora 30 with and gcc-9.2.1-1.fc30.x86_64. > > > > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au> > > --- > > hw/intc/exynos4210_gic.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/hw/intc/exynos4210_gic.c b/hw/intc/exynos4210_gic.c > > index a1b699b6ba..2e5e47f9ec 100644 > > --- a/hw/intc/exynos4210_gic.c > > +++ b/hw/intc/exynos4210_gic.c > > @@ -290,8 +290,8 @@ static void exynos4210_gic_realize(DeviceState *dev, > > Error **errp) > > SysBusDevice *sbd = SYS_BUS_DEVICE(obj); > > const char cpu_prefix[] = "exynos4210-gic-alias_cpu"; > > const char dist_prefix[] = "exynos4210-gic-alias_dist"; > > - char cpu_alias_name[sizeof(cpu_prefix) + 3]; > > - char dist_alias_name[sizeof(cpu_prefix) + 3]; > > + char cpu_alias_name[sizeof(cpu_prefix) + 10]; > > + char dist_alias_name[sizeof(cpu_prefix) + 10]; > > SysBusDevice *gicbusdev; > > uint32_t i; > > If we assert() that num_cpu is always <= EXYNOS4210_NCPUS > is that sufficient to clue gcc in that the buffer can't overflow?
Interestingly, assert(s->num_cpu <= EXYNOS$210_NCPUS) is *not*
sufficient, but assert(i <= EXYNOS4210_NCPUS) within the loop *is*
enough. I've updated my patch accordingly.
This isn't 4.2 material, obviously. Should I just sit on it until 5.0
opens, or does one of you have someplace to stage the patch in the
meanwhile?
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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