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    Subject[PATCH] sys: Fix missing rcu protection for sys_getpriority.
    Oleg Nesterov wrote:
    > This also fixes another bug here. find_task_by_vpid() is not safe
    > without rcu_read_lock(). I do not mean it is not safe to use the
    > result, just find_pid_ns() by itself is not safe.
    > Usually tasklist gives enough protection, but if copy_process() fails
    > it calls free_pid() lockless and does call_rcu(delayed_put_pid().
    > This means, without rcu lock find_pid_ns() can't scan the hash table
    > safely.

    This bug for sys_setpriority() was fixed, but not fixed for sys_getpriority().
    Why not to add it as well?
    [PATCH] sys: Fix missing rcu protection for sys_setpriority.

    find_task_by_vpid() is not safe without rcu_read_lock().
    2.6.33-rc7 got RCU protection for sys_setpriority() but missed it for

    Signed-off-by: Tetsuo Handa <>
    kernel/sys.c | 2 ++
    1 file changed, 2 insertions(+)

    --- linux-2.6.33-rc7.orig/kernel/sys.c
    +++ linux-2.6.33-rc7/kernel/sys.c
    @@ -222,6 +222,7 @@ SYSCALL_DEFINE2(getpriority, int, which,
    if (which > PRIO_USER || which < PRIO_PROCESS)
    return -EINVAL;

    + rcu_read_lock();
    switch (which) {
    case PRIO_PROCESS:
    @@ -267,6 +268,7 @@ SYSCALL_DEFINE2(getpriority, int, which,
    + rcu_read_unlock();

    return retval;

     \ /
      Last update: 2010-02-11 13:07    [W:0.019 / U:10.576 seconds]
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