Messages in this thread Patch in this message | | | From | Kangjie Lu <> | Subject | [PATCH v2] sched: fix a potential double-fetch bug in sched_copy_attr | Date | Wed, 9 Jan 2019 01:45:24 -0600 |
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"uattr->size" is copied in from user space and checked. However, it is copied in again after the security check. A malicious user may race to change it. The fix sets uattr->size to be the checked size.
Signed-off-by: Kangjie Lu <kjlu@umn.edu> --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 6fedf3a98581..e868cc25ac2a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4499,6 +4499,9 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a if (ret) return -EFAULT; + /* In case attr->size was changed in the user space */ + 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? -- 2.17.1
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