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b=OR6CtrMyxd1Z+5iO7Hv2ssq0rj4tInpiLXOHekiIBwb/YeDYw746Zw1WzNFdwScek O57e0v8xAwFIzR4SS4n8Alx8RU4zkP3aTFBY4cpAm7nUpbJ1sHBUavF8dRGFIOakIJ rxt5nVX0A3lI4DYBO5nu4fY8x1cdLfegQQESUk2+6J5spsytGwoMwnLvfhXgJ3gwmD yHaw9jRkuwHqlTdToEsiyHjvURQBvAOAYXNYiT6W7jz78JUKNdFPn10D7bsJteXipI 4fjoI6J1ijS0/v4GSyXzEbpTAaRxgz6By7HzrCMmk4jlq0WhnEAIiQG9cdJE9E1cxY af/t9EoSimxmw== Date: Thu, 9 Jan 2025 09:38:19 -0800 From: Kees Cook To: Tetsuo Handa Cc: Andrew Morton , linux-mm , LKML Subject: Re: [PATCH] mm/util: make memdup_user_nul() similar to memdup_user() Message-ID: <202501090937.221C3F6BA@keescook> References: <014cd694-cc27-4a07-a34a-2ae95d744515@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <014cd694-cc27-4a07-a34a-2ae95d744515@I-love.SAKURA.ne.jp> X-Rspamd-Server: rspam05 X-Stat-Signature: t4pajb8eomf1mxy8efgma8oty5qr63ub X-Rspamd-Queue-Id: 9070CC0003 X-Rspam-User: X-HE-Tag: 1736444303-75937 X-HE-Meta: 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 mLCfOT4K BDaquL7VQsUC2jyFb6CzyZzaaIGnj0YMkLikPn0RzUt7+MSsMiB37okK/WLDdhsavrgMjx/5A1sT8wZXyPmq3MkhOupAZhOXFlbH9HFQF07xrZR4DN/Xe7EyXtoMJ2D66+7WHBKwvYQGy5WgmLBnnAJsPj1a+ynaS7R9A3ju7DXVPccG0zslLI9+EkPASUbZvcomxddJl975Zz0XKwMGqANWpwTfZOoXaGUCX2wJGpNenWH/b8ZE272ptmjjHbqv3wAqs/uRjXEQjJ7tt39JnechIHerMoGdRLsiWFAz7d9IjkjbqS4dbAeqyrs5GusJckD5X6JmxXKjZbs82vaWeQqa18SQR6rCrUARCbRmzj+i6HbWj2DjL5FFfJa3U30nnEvUv7xiWzjYn4PzztUSStoOB14FiZ2fjb0lF1iGn+Begp697lneTQSeuOg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Dec 21, 2024 at 04:47:29PM +0900, Tetsuo Handa wrote: > 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@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=7e12e97b36154c54414b > Signed-off-by: Tetsuo Handa Thanks for this! Yes, please. With the commit log updated to answer akpm's questions: Acked-by: Kees Cook -Kees > --- > 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 -- Kees Cook