From: Kangjie Lu <kjlu@umn.edu>
To: kjlu@umn.edu
Cc: pakki001@umn.edu, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH v2] sched: fix a potential double-fetch bug in sched_copy_attr
Date: Wed, 9 Jan 2019 01:45:24 -0600 [thread overview]
Message-ID: <20190109074524.10176-1-kjlu@umn.edu> (raw)
In-Reply-To: <20190107171101.GI14122@hirez.programming.kicks-ass.net>
"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
next prev parent reply other threads:[~2019-01-09 7:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-25 22:16 [PATCH] sched: fix a potential double-fetch bug in sched_copy_attr Kangjie Lu
2019-01-07 17:11 ` Peter Zijlstra
2019-01-09 7:45 ` Kangjie Lu [this message]
2019-01-21 11:32 ` [tip:sched/core] sched/core: Fix a potential double-fetch bug in sched_copy_attr() tip-bot for Kangjie Lu
2019-01-27 11:04 ` Thomas Gleixner
2019-01-27 11:28 ` Ingo Molnar
2019-01-28 7:58 ` Peter Zijlstra
2019-01-28 13:15 ` Thomas Gleixner
2019-03-10 10:09 ` Thomas Gleixner
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