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sched: Fix information leak in sys_sched_getattr()

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We're copying the on-stack structure to userspace, but forgot to give
the right number of bytes to copy. This allows the calling process to
obtain up to PAGE_SIZE bytes from the stack (and possibly adjacent
kernel memory).

This fix copies only as much as we actually have on the stack
(attr->size defaults to the size of the struct) and leaves the rest of
the userspace-provided buffer untouched.

Found using kmemcheck + trinity.

Fixes: d50dde5a10f30 ("sched: Add new scheduler syscalls to support an extended scheduling parameters ABI")
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392585857-10725-1-git-send-email-vegard.nossum@oracle.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Vegard Nossum 2014-02-16 22:24:17 +01:00 committed by Thomas Gleixner
parent 3cf1962cdb
commit 4efbc454ba
1 changed files with 1 additions and 1 deletions
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2
kernel/sched/core.c
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@ -3786,7 +3786,7 @@ static int sched_read_attr(struct sched_attr __user *uattr,
attr->size = usize;
}
ret = copy_to_user(uattr, attr, usize);
ret = copy_to_user(uattr, attr, attr->size);
if (ret)
return -EFAULT;