[PATCH 3.14 33/78] sched: Make sched_setattr() correctly return -EFBIG

Greg Kroah-Hartman
2014-06-09T23:08:54Z

From: Michael Kerrisk <mtk.manpages@gmail.com>

commit 143cf23df25b7082cd706c3c53188e741e7881c3 upstream.

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: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/536CEC17.9070903@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/sched/core.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3680,8 +3680,9 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pi
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;

if (attr.sched_policy < 0)
return -EINVAL;