From: "Luck, Tony" <tony.luck@xxxxxxxxx> [ Upstream commit 61f259821dd3306e49b7d42a3f90fb5a4ff3351b ] Some processors may mispredict an array bounds check and speculatively access memory that they should not. With a user supplied array index we like to play things safe by masking the value with the array size before it is used as an index. Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx> Link: https://lore.kernel.org/r/20190731043957.GA1600@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/infiniband/core/user_mad.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c index 671f07ba1fad6..025b6d86a61fc 100644 --- a/drivers/infiniband/core/user_mad.c +++ b/drivers/infiniband/core/user_mad.c @@ -49,6 +49,7 @@ #include <linux/sched.h> #include <linux/semaphore.h> #include <linux/slab.h> +#include <linux/nospec.h> #include <linux/uaccess.h> @@ -883,11 +884,14 @@ static int ib_umad_unreg_agent(struct ib_umad_file *file, u32 __user *arg) if (get_user(id, arg)) return -EFAULT; + if (id >= IB_UMAD_MAX_AGENTS) + return -EINVAL; mutex_lock(&file->port->file_mutex); mutex_lock(&file->mutex); - if (id >= IB_UMAD_MAX_AGENTS || !__get_agent(file, id)) { + id = array_index_nospec(id, IB_UMAD_MAX_AGENTS); + if (!__get_agent(file, id)) { ret = -EINVAL; goto out; } -- 2.20.1
