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    Subject[PATCH v3 05/11] rlimits: allow setrlimit to non-current tasks
    Date
    From: Jiri Slaby <jirislaby@gmail.com>

    Add locking to allow setrlimit accept task parameter other than
    current.

    Namely, lock tasklist_lock for read and check whether the task
    structure has sighand non-null. Do all the signal processing under
    that lock still held.

    Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
    Cc: Oleg Nesterov <oleg@redhat.com>
    ---
    kernel/sys.c | 11 ++++++++++-
    1 files changed, 10 insertions(+), 1 deletions(-)
    diff --git a/kernel/sys.c b/kernel/sys.c
    index 7c76f84..eb21661 100644
    --- a/kernel/sys.c
    +++ b/kernel/sys.c
    @@ -1272,6 +1272,7 @@ SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,

    #endif

    +/* make sure you are allowed to change @tsk limits before calling this */
    int do_setrlimit(struct task_struct *tsk, unsigned int resource,
    struct rlimit *new_rlim)
    {
    @@ -1285,9 +1286,16 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource,
    if (resource == RLIMIT_NOFILE && new_rlim->rlim_max > sysctl_nr_open)
    return -EPERM;

    + /* protect tsk->signal and tsk->sighand from disappearing */
    + read_lock(&tasklist_lock);
    + if (!tsk->sighand) {
    + retval = -ESRCH;
    + goto out;
    + }
    +
    retval = security_task_setrlimit(tsk, resource, new_rlim);
    if (retval)
    - return retval;
    + goto out;

    if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) {
    /*
    @@ -1322,6 +1330,7 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource,

    update_rlimit_cpu(tsk, new_rlim->rlim_cur);
    out:
    + read_unlock(&tasklist_lock);
    return retval;
    }

    --
    1.7.1



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