The patch titled
Subject: mm/util: make memdup_user_nul() similar to memdup_user()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-util-make-memdup_user_nul-similar-to-memdup_user.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-util-make-memdup_user_nul-similar-to-memdup_user.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Subject: mm/util: make memdup_user_nul() similar to memdup_user()
Date: Sat, 21 Dec 2024 16:47:29 +0900
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.
Link: https://lkml.kernel.org/r/014cd694-cc27-4a07-a34a-2ae95d744515@xxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+7e12e97b36154c54414b@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=7e12e97b36154c54414b
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/util.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
--- a/mm/util.c~mm-util-make-memdup_user_nul-similar-to-memdup_user
+++ a/mm/util.c
@@ -297,12 +297,7 @@ void *memdup_user_nul(const void __user
{
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);
_
Patches currently in -mm which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
mm-util-make-memdup_user_nul-similar-to-memdup_user.patch
