| From a3671a4f973ee9d9621d60166cc3b037c397d604 Mon Sep 17 00:00:00 2001 |
| From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> |
| Date: Tue, 16 Oct 2018 16:59:01 +0200 |
| Subject: RDMA/ucma: Fix Spectre v1 vulnerability |
| |
| From: Gustavo A. R. Silva <gustavo@embeddedor.com> |
| |
| commit a3671a4f973ee9d9621d60166cc3b037c397d604 upstream. |
| |
| 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> |
| Signed-off-by: Doug Ledford <dledford@redhat.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/infiniband/core/ucma.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- 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> |
| @@ -1637,6 +1639,7 @@ static ssize_t ucma_write(struct file *f |
| |
| 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; |
