Date: Mon, 25 Mar 2019 01:42:07 +0300 From: Aleksey Cherepanov <lyosha@...nwall.com> To: john-users@...ts.openwall.com Subject: can other user access secrets in GPU's memory? I was playing around with OpenCL and it looks like memory is not zeroed by default on GPUs, i.e. I can read old values from gpu on another run of host program. So I guess it means that other users can read these values too, right? Does john clean up memory after work to avoid this? Or is it unusual to run john on a shared machine/gpu? To be certain, I used code from the following tutorial: https://community.nxp.com/docs/DOC-93984 I tried the code. Then I modified WorkSize to 1 and got same values. Then I modified + to * in the kernel and got the first value as with * and other values as with +. So they were old and survived between runs. I tried that on vega card on Openwall's super: CL_DEVICE_NAME: gfx900 CL_DRIVER_VERSION: 2766.4 (PAL,HSAIL) Thanks! -- Regards, Aleksey Cherepanov
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