2014-02-16 21:25:09

by Vegard Nossum

Subject: [PATCH] sched: fix information leak in sys_sched_getattr()

From: Vegard Nossum <[email protected]>

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 <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Vegard Nossum <[email protected]>
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b46131e..ac939c3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -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;

--
1.7.10.4

2014-02-21 20:33:09

by tip-bot for Vasyl Gomonovych

Subject: [tip:sched/urgent] sched: Fix information leak in sys_sched_getattr()

Commit-ID: 4efbc454ba68def5ef285b26ebfcfdb605b52755
Gitweb: http://git.kernel.org/tip/4efbc454ba68def5ef285b26ebfcfdb605b52755
Author: Vegard Nossum <[email protected]>
AuthorDate: Sun, 16 Feb 2014 22:24:17 +0100
Committer: Thomas Gleixner <[email protected]>
CommitDate: Fri, 21 Feb 2014 21:27:10 +0100

sched: Fix information leak in sys_sched_getattr()

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 <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Vegard Nossum <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 33d030a..a6e7470 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -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;