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    SubjectRe: [PATCH 1/2] exec: Make do_coredump more robust and safer when using pipes in core_pattern: recursive dump detection
    On 06/26, Neil Horman wrote:
    >
    > + if (core_limit == 0) {
    > + /*
    > + * Normally core limits are irrelevant to pipes, since
    > + * we're not writing to the file system, but we use
    > + * core_limit of 0 here as a speacial value. Any
    > + * non-zero limit gets set to RLIM_INFINITY below, but
    > + * a limit of 0 skips the dump. This is a consistent
    > + * way to catch recursive crashes. We can still crash
    > + * if the core_pattern binary sets RLIM_CORE = !0
    > + * but it runs as root, and can do lots of stupid things
    > + * Note that we use task_tgid_vnr here to grab the pid of the
    > + * process group leader. That way we get the right pid if a thread
    > + * in a multi-threaded core_pattern process dies.
    > + */
    > + printk(KERN_WARNING "Process %d(%s) has RLIMIT_CORE set to 0\n",
    > + task_tgid_vnr(current), current->comm);
    > + printk(KERN_WARNING "Aborting core\n");

    Andrew has already pointed out this, unprivileged-user-triggerable
    printk.

    Doesn't look good, if core_pattern starts with "|" any user can set
    RLIMIT_CORE = 0 and then just do

    for (;;)
    if (pid = fork())
    kill(pid, SIGQUIT);

    to DOS printk/syslog, no?

    Oleg.



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