From bc500cd4b469ef37d167f24025f62d4ed87372b8 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Tue, 16 Oct 2018 16:32:40 +0200 Subject: IB/ucm: Fix Spectre v1 vulnerability commit 0295e39595e1146522f2722715dba7f7fba42217 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/ucm.c:1127 ib_ucm_write() warn: potential spectre issue 'ucm_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 Signed-off-by: Gustavo A. R. Silva Signed-off-by: Doug Ledford [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- drivers/infiniband/core/ucm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c index 5befec118a18..23b72417a433 100644 --- a/drivers/infiniband/core/ucm.c +++ b/drivers/infiniband/core/ucm.c @@ -46,6 +46,8 @@ #include #include +#include + #include #include @@ -1116,6 +1118,7 @@ static ssize_t ib_ucm_write(struct file *filp, const char __user *buf, if (hdr.cmd >= ARRAY_SIZE(ucm_cmd_table)) return -EINVAL; + hdr.cmd = array_index_nospec(hdr.cmd, ARRAY_SIZE(ucm_cmd_table)); if (hdr.in + sizeof(hdr) > len) return -EINVAL; -- cgit v1.2.3