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 <[email protected]> --- V2: Mask the index *AFTER* the bounds check. Issue pointed out by Gustavo. Fix suggested by Ira. drivers/infiniband/core/user_mad.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c index 9f8a48016b41..32cea5ed9ce1 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> @@ -888,7 +889,12 @@ static int ib_umad_unreg_agent(struct ib_umad_file *file, u32 __user *arg) mutex_lock(&file->port->file_mutex); mutex_lock(&file->mutex); - if (id >= IB_UMAD_MAX_AGENTS || !__get_agent(file, id)) { + if (id >= IB_UMAD_MAX_AGENTS) { + ret = -EINVAL; + goto out; + } + id = array_index_nospec(id, IB_UMAD_MAX_AGENTS); + if (!__get_agent(file, id)) { ret = -EINVAL; goto out; } -- 2.20.1
