Commit 143cf23d authored May 09, 2014 by Michael Kerrisk Committed by Ingo Molnar May 22, 2014

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>

parent 2b4cfe64

kernel/sched/core.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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;

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