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Date: Thu, 02 Dec 2004 13:53:13 -0800
From: Prasanna Meda <pmeda@akamai.com>
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To: akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sys_set/getpriority PRIO_USER semantics fix and optimisation
References: <200412012321.PAA30853@allur.sanmateo.akamai.com>
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pmeda@akamai.com wrote:

> sys_set/getpriority is rewritten in 2.5/2.6, perhaps while transitioning
> to the pid maps.  It has now semantical bug, when uid is zero.  Note

A test case:

#include <stdio.h>
#include <sys/time.h>
#include <sys/resource.h>

int main()
{
        int prio1, prio2, ret, errno;

        /* If root, loose priv. for testing */
        setresuid(237, 237, 237);

        prio1 = getpriority(2, getuid());
        if (setpriority(PRIO_USER, 0, prio1+1) < 0) {
                perror("setprio");
                printf("FAILED!\n");
        }
        else {
                prio2 = getpriority(2, getuid());
                printf("Old prio:%d to new prio:%d\n", prio1, prio2);
                printf((prio1 +1 != prio2)? "FAILED\n":"PASSED\n");
        }
        exit(0);
}