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@xxxxxxxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> --- 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
