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Re: [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer ove
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow |
Date: |
Tue, 15 May 2018 20:27:49 +0100 |
User-agent: |
mu4e 1.1.0; emacs 26.1 |
Peter Maydell <address@hidden> writes:
> Coverity complains about qemu_memfd_create() (CID 1385858) because
> we calculate a bit position htsize which could be up to 63, but
> then use it in "1 << htsize" which is a 32-bit integer calculation
> and could push the 1 off the top of the value.
>
> Silence the complaint bu using "1ULL"; this isn't a bug in
> practice since a hugetlbsize of 4GB is not very plausible.
>
> Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
> ---
> util/memfd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/util/memfd.c b/util/memfd.c
> index b3ecbac19e..d248a53c3c 100644
> --- a/util/memfd.c
> +++ b/util/memfd.c
> @@ -66,7 +66,7 @@ int qemu_memfd_create(const char *name, size_t size, bool
> hugetlb,
> {
> int htsize = hugetlbsize ? ctz64(hugetlbsize) : 0;
>
> - if (htsize && 1 << htsize != hugetlbsize) {
> + if (htsize && 1ULL << htsize != hugetlbsize) {
> error_setg(errp, "Hugepage size must be a power of 2");
> return -1;
> }
--
Alex Bennée