Commit-ID: 120e4e76857ddbc9268e1aa3f9de61a498e84618 Gitweb: https://git.kernel.org/tip/120e4e76857ddbc9268e1aa3f9de61a498e84618 Author: Kangjie Lu <kjlu@xxxxxxx> AuthorDate: Wed, 9 Jan 2019 01:45:24 -0600 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Mon, 21 Jan 2019 11:26:17 +0100 sched/core: Fix a potential double-fetch bug in sched_copy_attr() "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@xxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: pakki001@xxxxxxx Cc: <stable@xxxxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20190109074524.10176-1-kjlu@xxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a674c7db2f29..d4d3514c4fe9 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 by 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?
