Re: [PATCH libdrm 2/2] include: Avoid potentially infinite loop in log2_int().

On 10/30/20 14:07, Pekka Paalanen wrote:

On Wed, 28 Oct 2020 13:06:02 +0300 Paul Gofman pgofman@codeweavers.com wrote:

...

Signed-off-by: Paul Gofman pgofman@codeweavers.com

util_math.h | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/util_math.h b/util_math.h index e2fa95f5..f6bbe192 100644 --- a/util_math.h +++ b/util_math.h @@ -38,6 +38,9 @@ static inline unsigned log2_int(unsigned x) if (x < 2) { return 0; }

• if (x & 0x80000000) {

•    return 31;
  

• } for (l = 2; ; l++) { if ((unsigned)(1 << l) > x) { return l - 1;

Hi,

I guess that does it, but it seems quite a lot of code that could be a two-liner: http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious

Thanks, pq

Hello,

thanks, I've sent the updated patches with simplified implementation.

Regards,

Paul.