Messages in this thread Patch in this message | | | From | Meng Xu <> | Subject | [PATCH] sched/core: Fix a potential double fetch bug on attr->size | Date | Mon, 25 Sep 2017 08:53:16 -0400 |
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From: Meng Xu <mengxu.gatech@gmail.com>
`attr->size` after the second fetch `copy_from_user(attr, uattr, size)`, can be different from what is initially fetched in and checked `get_user(size, &uattr->size)` by racing condition in the userspace.
The issue and the patch are both similar to commit f12f42a (in kernel/events/core.c).
Signed-off-by: Meng Xu <mengxu.gatech@gmail.com> --- kernel/sched/core.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0869b20..c22d2b4 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4349,6 +4349,8 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a if (ret) return -EFAULT; + attr->size = size; + /* * XXX: Do we want to be lenient like existing syscalls; or do we want * to be strict and return an error on out-of-bounds values? -- 2.7.4
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