* [PATCH] RDMA/ucma: Fix Spectre v1 vulnerability
@ 2018-10-16 14:59 Gustavo A. R. Silva
2018-10-16 16:49 ` Doug Ledford
0 siblings, 1 reply; 3+ messages in thread
From: Gustavo A. R. Silva @ 2018-10-16 14:59 UTC (permalink / raw)
To: Doug Ledford, Jason Gunthorpe
Cc: linux-rdma, linux-kernel, Gustavo A. R. Silva
hdr.cmd can be indirectly controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
drivers/infiniband/core/ucma.c:1686 ucma_write() warn: potential
spectre issue 'ucma_cmd_table' [r] (local cap)
Fix this by sanitizing hdr.cmd before using it to index
ucm_cmd_table.
Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/infiniband/core/ucma.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 21863dd..01d68ed 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -44,6 +44,8 @@
#include <linux/module.h>
#include <linux/nsproxy.h>
+#include <linux/nospec.h>
+
#include <rdma/rdma_user_cm.h>
#include <rdma/ib_marshall.h>
#include <rdma/rdma_cm.h>
@@ -1676,6 +1678,7 @@ static ssize_t ucma_write(struct file *filp, const char __user *buf,
if (hdr.cmd >= ARRAY_SIZE(ucma_cmd_table))
return -EINVAL;
+ hdr.cmd = array_index_nospec(hdr.cmd, ARRAY_SIZE(ucma_cmd_table));
if (hdr.in + sizeof(hdr) > len)
return -EINVAL;
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] RDMA/ucma: Fix Spectre v1 vulnerability
2018-10-16 14:59 [PATCH] RDMA/ucma: Fix Spectre v1 vulnerability Gustavo A. R. Silva
@ 2018-10-16 16:49 ` Doug Ledford
2018-10-18 8:13 ` Gustavo A. R. Silva
0 siblings, 1 reply; 3+ messages in thread
From: Doug Ledford @ 2018-10-16 16:49 UTC (permalink / raw)
To: Gustavo A. R. Silva, Jason Gunthorpe; +Cc: linux-rdma, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 999 bytes --]
On Tue, 2018-10-16 at 16:59 +0200, Gustavo A. R. Silva wrote:
> hdr.cmd can be indirectly controlled by user-space, hence leading to
> a potential exploitation of the Spectre variant 1 vulnerability.
>
> This issue was detected with the help of Smatch:
>
> drivers/infiniband/core/ucma.c:1686 ucma_write() warn: potential
> spectre issue 'ucma_cmd_table' [r] (local cap)
>
> Fix this by sanitizing hdr.cmd before using it to index
> ucm_cmd_table.
>
> Notice that given that speculation windows are large, the policy is
> to kill the speculation on the first load and not worry if it can be
> completed with a dependent load/store [1].
>
> [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Thanks, applied to for-rc.
--
Doug Ledford <dledford@redhat.com>
GPG KeyID: B826A3330E572FDD
Key fingerprint = AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD
[-- Attachment #2: This is a digitally signed message part --]
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] RDMA/ucma: Fix Spectre v1 vulnerability
2018-10-16 16:49 ` Doug Ledford
@ 2018-10-18 8:13 ` Gustavo A. R. Silva
0 siblings, 0 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2018-10-18 8:13 UTC (permalink / raw)
To: Doug Ledford, Jason Gunthorpe; +Cc: linux-rdma, linux-kernel
On 10/16/18 6:49 PM, Doug Ledford wrote:
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>
> Thanks, applied to for-rc.
>
Thanks, Doug.
--
Gustavo
^ permalink raw reply [flat|nested] 3+ messages in thread
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