[PATCH for-5.2] util/cutils: Fix bounds check at freq_to_str()

[PATCH for-5.2] util/cutils: Fix bounds check at freq_to_str()

[Eduardo Habkost]

Fix bounds check for idx at freq_to_str(), to actually ensure idx
never goes beyond the last element of the suffixes array.

Reported-by: Coverity (CID 1435957: OVERRUN)
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 util/cutils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/cutils.c b/util/cutils.c
index c395974fab..0d9261e1e5 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -891,7 +891,7 @@ char *freq_to_str(uint64_t freq_hz)
     double freq = freq_hz;
     size_t idx = 0;
 
-    while (freq >= 1000.0 && idx < ARRAY_SIZE(suffixes)) {
+    while (freq >= 1000.0 && idx < ARRAY_SIZE(suffixes) - 1) {
         freq /= 1000.0;
         idx++;
     }
-- 
2.28.0

Re: [PATCH for-5.2] util/cutils: Fix bounds check at freq_to_str()

[Philippe Mathieu-Daudé]

On 10/29/20 9:38 PM, Eduardo Habkost wrote:
> Fix bounds check for idx at freq_to_str(), to actually ensure idx
> never goes beyond the last element of the suffixes array.
> 
> Reported-by: Coverity (CID 1435957: OVERRUN)
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  util/cutils.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/util/cutils.c b/util/cutils.c
> index c395974fab..0d9261e1e5 100644
> --- a/util/cutils.c
> +++ b/util/cutils.c
> @@ -891,7 +891,7 @@ char *freq_to_str(uint64_t freq_hz)
>      double freq = freq_hz;
>      size_t idx = 0;
>  
> -    while (freq >= 1000.0 && idx < ARRAY_SIZE(suffixes)) {
> +    while (freq >= 1000.0 && idx < ARRAY_SIZE(suffixes) - 1) {

This was the first patch I wrote, but thought this wasn't the
simplest way. Probably too tired.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Thanks.

>          freq /= 1000.0;
>          idx++;
>      }
> 

Re: [PATCH for-5.2] util/cutils: Fix bounds check at freq_to_str()

[Peter Maydell]

On Thu, 29 Oct 2020 at 20:38, Eduardo Habkost <ehabkost@redhat.com> wrote:
>
> Fix bounds check for idx at freq_to_str(), to actually ensure idx
> never goes beyond the last element of the suffixes array.
>
> Reported-by: Coverity (CID 1435957: OVERRUN)
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>

Personally I preferred the other option (remove the
idx check from the while loop and assert that idx
is in bounds after the loop)...

> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

thanks
-- PMM