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authorKees Cook <keescook@chromium.org>2017-11-30 13:04:32 -0800
committerKees Cook <keescook@chromium.org>2018-01-15 12:07:48 -0800
commit2d891fbc3bb681ba1f826e7ee70dbe38ca7465fe (patch)
tree1dac3dd3aac5a0fed8046b6f85bd944211260c70 /mm/slab.c
parentafcc90f8621e289cd082ba97900e76f01afe778c (diff)
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usercopy: Allow strict enforcement of whitelists
This introduces CONFIG_HARDENED_USERCOPY_FALLBACK to control the behavior of hardened usercopy whitelist violations. By default, whitelist violations will continue to WARN() so that any bad or missing usercopy whitelists can be discovered without being too disruptive. If this config is disabled at build time or a system is booted with "slab_common.usercopy_fallback=0", usercopy whitelists will BUG() instead of WARN(). This is useful for admins that want to use usercopy whitelists immediately. Suggested-by: Matthew Garrett <mjg59@google.com> Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'mm/slab.c')
-rw-r--r--mm/slab.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 1c02f6e94235..b9b0df620bb9 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4426,7 +4426,8 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page,
* to be a temporary method to find any missing usercopy
* whitelists.
*/
- if (offset <= cachep->object_size &&
+ if (usercopy_fallback &&
+ offset <= cachep->object_size &&
n <= cachep->object_size - offset) {
usercopy_warn("SLAB object", cachep->name, to_user, offset, n);
return;