sched: Make sched_setattr() correctly return -EFBIG

The documented[1] behavior of sched_attr() in the proposed man page text is:

    sched_attr::size must be set to the size of the structure, as in
    sizeof(struct sched_attr), if the provided structure is smaller
    than the kernel structure, any additional fields are assumed
    '0'. If the provided structure is larger than the kernel structure,
    the kernel verifies all additional fields are '0' if not the
    syscall will fail with -E2BIG.

As currently implemented, sched_copy_attr() returns -EFBIG for
for this case, but the logic in sys_sched_setattr() converts that
error to -EFAULT. This patch fixes the behavior.

[1] http://thread.gmane.org/gmane.linux.kernel/1615615/focus=1697760

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/536CEC17.9070903@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Michael Kerrisk 2014-05-09 16:54:15 +02:00 committed by Ingo Molnar
parent 2b4cfe64de
commit 143cf23df2

View File

@ -3658,8 +3658,9 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
if (!uattr || pid < 0 || flags)
return -EINVAL;
if (sched_copy_attr(uattr, &attr))
return -EFAULT;
retval = sched_copy_attr(uattr, &attr);
if (retval)
return retval;
rcu_read_lock();
retval = -ESRCH;