2019-05-30 01:12:57

by Gen Zhang

Subject: [PATCH] mpt3sas_ctl: fix double-fetch bug in _ctl_ioctl_main()

In _ctl_ioctl_main(), 'ioctl_header' is fetched the first time from
userspace. 'ioctl_header.ioc_number' is then checked. The legal result
is saved to 'ioc'. Then, in condition MPT3COMMAND, the whole struct is
fetched again from the userspace. Then _ctl_do_mpt_command() is called,
'ioc' and 'karg' as inputs.

However, a malicious user can change the 'ioc_number' between the two
fetches, which will cause a potential security issues. Moreover, a
malicious user can provide a valid 'ioc_number' to pass the check in
first fetch, and then modify it in the second fetch.

To fix this, we need to recheck the 'ioc_number' in the second fetch.

Signed-off-by: Gen Zhang <[email protected]>
Ack-by: Suganath Prabu S <[email protected]>
---
diff --git a/drivers/scsi/mpt3sas/mpt3sas_ctl.c b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
index b2bb47c..5181c03 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_ctl.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
@@ -2319,6 +2319,10 @@ _ctl_ioctl_main(struct file *file, unsigned int cmd, void __user *arg,
break;
}

+ if (karg.hdr.ioc_number != ioctl_header.ioc_number) {
+ ret = -EINVAL;
+ break;
+ }
if (_IOC_SIZE(cmd) == sizeof(struct mpt3_ioctl_command)) {
uarg = arg;
ret = _ctl_do_mpt_command(ioc, karg, &uarg->mf);

2019-05-30 02:23:34

by Martin K. Petersen

Subject: Re: [PATCH] mpt3sas_ctl: fix double-fetch bug in _ctl_ioctl_main()

Gen,

> In _ctl_ioctl_main(), 'ioctl_header' is fetched the first time from
> userspace. 'ioctl_header.ioc_number' is then checked. The legal result
> is saved to 'ioc'. Then, in condition MPT3COMMAND, the whole struct is
> fetched again from the userspace. Then _ctl_do_mpt_command() is called,
> 'ioc' and 'karg' as inputs.
>
> However, a malicious user can change the 'ioc_number' between the two
> fetches, which will cause a potential security issues. Moreover, a
> malicious user can provide a valid 'ioc_number' to pass the check in
> first fetch, and then modify it in the second fetch.
>
> To fix this, we need to recheck the 'ioc_number' in the second fetch.

Applied to 5.3/scsi-queue, thanks.

--
Martin K. Petersen Oracle Linux Engineering