This is a note to let you know that I've just added the patch titled RDMA/ucma: Fix Spectre v1 vulnerability to the 4.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rdma-ucma-fix-spectre-v1-vulnerability.patch and it can be found in the queue-4.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a3671a4f973ee9d9621d60166cc3b037c397d604 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> Date: Tue, 16 Oct 2018 16:59:01 +0200 Subject: RDMA/ucma: Fix Spectre v1 vulnerability From: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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> @@ -1676,6 +1678,7 @@ 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; Patches currently in stable-queue which might be from gustavo@xxxxxxxxxxxxxx are queue-4.18/ptp-fix-spectre-v1-vulnerability.patch queue-4.18/rdma-ucma-fix-spectre-v1-vulnerability.patch queue-4.18/usb-gadget-storage-fix-spectre-v1-vulnerability.patch queue-4.18/ib-ucm-fix-spectre-v1-vulnerability.patch