Since the string data to copy from userspace is likely less than PAGE_SIZE
bytes, replace GFP_KERNEL with GFP_USER like commit 6c2c97a24f09
("memdup_user(): switch to GFP_USER") does and add __GFP_NOWARN like commit
6c8fcc096be9 ("mm: don't let userspace spam allocations warnings") does.
Also, use dedicated slab buckets like commit d73778e4b867 ("mm/util: Use
dedicated slab buckets for memdup_user()") does.
Reported-by: syzbot+7e12e97b36154c54414b@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=7e12e97b36154c54414b
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
mm/util.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/mm/util.c b/mm/util.c
index c1c3b06ab4f9..60aa40f612b8 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -297,12 +297,7 @@ void *memdup_user_nul(const void __user *src, size_t len)
{
char *p;
- /*
- * Always use GFP_KERNEL, since copy_from_user() can sleep and
- * cause pagefault, which makes it pointless to use GFP_NOFS
- * or GFP_ATOMIC.
- */
- p = kmalloc_track_caller(len + 1, GFP_KERNEL);
+ p = kmem_buckets_alloc_track_caller(user_buckets, len + 1, GFP_USER | __GFP_NOWARN);
if (!p)
return ERR_PTR(-ENOMEM);
--
2.43.5
