* [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow
@ 2018-05-15 17:27 Peter Maydell
2018-05-15 18:14 ` Marc-André Lureau
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Peter Maydell @ 2018-05-15 17:27 UTC (permalink / raw)
To: qemu-devel; +Cc: patches, Paolo Bonzini, Marc-André Lureau
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 <peter.maydell@linaro.org>
---
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;
}
--
2.17.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow
2018-05-15 17:27 [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow Peter Maydell
@ 2018-05-15 18:14 ` Marc-André Lureau
2018-05-15 19:27 ` Alex Bennée
2018-05-16 7:23 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Marc-André Lureau @ 2018-05-15 18:14 UTC (permalink / raw)
To: Peter Maydell; +Cc: QEMU, Paolo Bonzini, patches
On Tue, May 15, 2018 at 7:27 PM, Peter Maydell <peter.maydell@linaro.org> wrote:
> 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 <peter.maydell@linaro.org>
Thanks Peter for the fix,
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
> 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;
> }
> --
> 2.17.0
>
>
--
Marc-André Lureau
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow
2018-05-15 17:27 [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow Peter Maydell
2018-05-15 18:14 ` Marc-André Lureau
@ 2018-05-15 19:27 ` Alex Bennée
2018-05-16 7:23 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Alex Bennée @ 2018-05-15 19:27 UTC (permalink / raw)
To: Peter Maydell; +Cc: qemu-devel, Paolo Bonzini, Marc-André Lureau, patches
Peter Maydell <peter.maydell@linaro.org> 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 <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
> ---
> 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
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow
2018-05-15 17:27 [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow Peter Maydell
2018-05-15 18:14 ` Marc-André Lureau
2018-05-15 19:27 ` Alex Bennée
@ 2018-05-16 7:23 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2018-05-16 7:23 UTC (permalink / raw)
To: Peter Maydell, qemu-devel; +Cc: patches, Marc-André Lureau
On 15/05/2018 19:27, Peter Maydell wrote:
> 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 <peter.maydell@linaro.org>
> ---
> 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;
> }
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-05-16 7:23 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-05-15 17:27 [Qemu-devel] [PATCH] memfd: Avoid Coverity warning about integer overflow Peter Maydell
2018-05-15 18:14 ` Marc-André Lureau
2018-05-15 19:27 ` Alex Bennée
2018-05-16 7:23 ` Paolo Bonzini
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).