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Tue, 3 Jan 2023 09:49:22 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <38352801-b4ae-0cdc-17ba-06b363da3aa6@I-love.SAKURA.ne.jp> Date: Tue, 3 Jan 2023 09:49:22 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH] fs/ntfs3: Use __GFP_NOWARN allocation at ntfs_load_attr_list() Content-Language: en-US To: Michal Hocko Cc: almaz.alexandrovich@paragon-software.com, ntfs3@lists.linux.dev, syzbot , syzkaller-bugs@googlegroups.com, linux-mm References: <00000000000027524405f1452ea8@google.com> <7b10c1aa-0b3a-da0d-ea0e-b135cffc3491@I-love.SAKURA.ne.jp> From: Tetsuo Handa In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: D34144000C X-Stat-Signature: jjbbh4ogdc7xaiqsazkxz1oyuqkw1m99 X-HE-Tag: 1672707278-760742 X-HE-Meta: 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 9Pa/iJtA okfWqKbHmps0BlfhE80wwiUCKuSYRDz8vW08O 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: On 2023/01/03 5:19, Michal Hocko wrote: >> @@ -52,7 +52,7 @@ int ntfs_load_attr_list(struct ntfs_inode *ni, struct ATTRIB *attr) >> >> if (!attr->non_res) { >> lsize = le32_to_cpu(attr->res.data_size); >> - le = kmalloc(al_aligned(lsize), GFP_NOFS); >> + le = kmalloc(al_aligned(lsize), GFP_NOFS | __GFP_NOWARN); > > This looks like a bad idea in general. The allocator merely says that > something is wrong and you are silencing that. The calling code should > check the size for reasonable range and if larger size. Moreover, if > lsize can be really more than PAGE_SIZE this should be kvmalloc instead. There are already similar commits. commit 0d0f659bf713 ("fs/ntfs3: Use __GFP_NOWARN allocation at wnd_init()") commit 59bfd7a483da ("fs/ntfs3: Use __GFP_NOWARN allocation at ntfs_fill_super()") Is KMALLOC_MAX_SIZE intended to be used by callers like https://linux.googlesource.com/linux/kernel/git/torvalds/linux/+/a5a1e1f249db4e0a35d3deca0b9916b11cc1f02b%5E! ? I think that, unless there is a known upper limit defined by specification, checking for overflow and silence like https://lkml.kernel.org/r/6d878e01-6c2f-8766-2578-c95030442369@I-love.SAKURA.ne.jp is fine. These input are random values which do not need to succeed by using kvmalloc().