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IB/core: Add mitigation for Spectre V1

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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@intel.com>
Link: https://lore.kernel.org/r/20190731043957.GA1600@agluck-desk2.amr.corp.intel.com
Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Luck, Tony 2019-07-30 21:39:57 -07:00 committed by Doug Ledford
parent 708637e65a
commit 61f259821d
1 changed files with 5 additions and 1 deletions
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6
drivers/infiniband/core/user_mad.c
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@ -49,6 +49,7 @@
#include <linux/sched.h>
#include <linux/semaphore.h>
#include <linux/slab.h>
#include <linux/nospec.h>
#include <linux/uaccess.h>
@ -884,11 +885,14 @@ 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;
}