From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
commit 739790605705ddcf18f21782b9c99ad7d53a8c11 upstream.
do_prlimit() adds the user-controlled resource value to a pointer that
will subsequently be dereferenced. In order to help prevent this
codepath from being used as a spectre "gadget" a barrier needs to be
added after checking the range.
Reported-by: Jordy Zomer <jordyzomer@xxxxxxxxxx>
Tested-by: Jordy Zomer <jordyzomer@xxxxxxxxxx>
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sys.c | 2 ++
1 file changed, 2 insertions(+)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1534,6 +1534,8 @@ int do_prlimit(struct task_struct *tsk,
if (resource >= RLIM_NLIMITS)
return -EINVAL;
+ resource = array_index_nospec(resource, RLIM_NLIMITS);
+
if (new_rlim) {
if (new_rlim->rlim_cur > new_rlim->rlim_max)
return -EINVAL;
